All India Electrical Engineering (EE) Group
Phase lead occurs at: - a) low frequency regions
- b)high frequency regions
- c)moderate frequencies
- d)very low frequency regions
Correct answer is option 'B'. Can you explain this answer?
Phase lead occurs at:
a)
low frequency regions
b)
high frequency regions
c)
moderate frequencies
d)
very low frequency regions
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Gate Funda answered |
Phase lead occurs in phase lead compensator and it occurs at the high-frequency region.
Lead compensator:
Transfer function:
Transfer function:
If it is in the form of 
then a < 1
then a < 1If it is in the form of 
then a > b
Maximum phase lag frequency: ωm = 1√Ta
Maximum phase lag::
then a > bMaximum phase lag frequency: ωm = 1√Ta
Maximum phase lag::
ϕm is positive
Pole zero plot:
The zero is nearer to the origin.
Filter: It is a high pass filter (HPF)
Effect on the system:
Filter: It is a high pass filter (HPF)
Effect on the system:
- Rise time and settling time decreases and Bandwidth increases
- The transient response becomes faster
- The steady-state response is not affected
- Improves the stability
A compensator with the transfer function G(s) = 
can give maximum gain of- a)-20 dB
- b)-10 dB
- c)0 dB
- d)20 dB
Correct answer is option 'C'. Can you explain this answer?
A compensator with the transfer function G(s) = can give maximum gain of
can give maximum gain ofa)
-20 dB
b)
-10 dB
c)
0 dB
d)
20 dB
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EduRev GATE answered |
For all ω Numerator is less than Denominator maximum value of |G(s)| occurs at ω = 0
|G(s)|max = 1
In dB, 20 log (1) = 0 dB
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Kanhai Lal
asked a question
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In a split phase motor- a)the starting winding is connected through a centrifugal switch
- b)the running winding is connected through a centrifugal switch
- c)both starting and running windings are connected through a centrifugal switch
- d)centrifugal switch is used to control supply voltage
Correct answer is option 'A'. Can you explain this answer?
In a split phase motor
a)
the starting winding is connected through a centrifugal switch
b)
the running winding is connected through a centrifugal switch
c)
both starting and running windings are connected through a centrifugal switch
d)
centrifugal switch is used to control supply voltage
Which of the following is not correct with respect to a phase-lead compensation network?- a)It increases system bandwidth
- b)It increases gain at higher frequencies
- c)It is used when fast transient response is required
- d)It is used when decrease rapidly near crossover frequency
Correct answer is option 'D'. Can you explain this answer?
Which of the following is not correct with respect to a phase-lead compensation network?
a)
It increases system bandwidth
b)
It increases gain at higher frequencies
c)
It is used when fast transient response is required
d)
It is used when decrease rapidly near crossover frequency
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EduRev GATE answered |
Lead compensator:
Transfer function:
Transfer function:
If it is in the form of then a < 1
then a < 1If it is in the form of then a > b
Maximum phase lag frequency:
ωm = 1√Ta
Maximum phase lag::
then a > bMaximum phase lag frequency:
ωm = 1√Ta
Maximum phase lag::
ϕm is positive
Pole zero plot:
The zero is nearer to the origin.
Filter: It is a high pass filter (HPF)
Effect on the system:
Filter: It is a high pass filter (HPF)
Effect on the system:
- Rise time and settling time decreases and Bandwidth increases
- The transient response becomes faster
- The steady-state response is not affected
- Improves the stability
- The velocity constant is usually increased
- Helps to increase the system error constant though to a limited extent
- The slope of the magnitude curve is reduced at the gain crossover frequency, as a result, relative stability improves
- The margin of stability of a system (phase margin) increased
For the network shown in the figure below, the frequency (in rad/s) at which the maximum phase lag occurs is, ___________.
Correct answer is between '0.30,0.33'. Can you explain this answer?
For the network shown in the figure below, the frequency (in rad/s) at which the maximum phase lag occurs is, ___________.
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EduRev GATE answered |
Given circuit is a lag compensator and transfer function is given as
On comparison we get, T = 1
βT = 10 ⇒ β = 10
The frequency at which maximum lead occurs is ωm = 1/T√β
On comparison we get, T = 1
βT = 10 ⇒ β = 10
The frequency at which maximum lead occurs is ωm = 1/T√β
The compensator required to improve the steady state response of a system is- a)Lag
- b)Lead
- c)Lag-lead
- d)Zero
Correct answer is option 'A'. Can you explain this answer?
The compensator required to improve the steady state response of a system is
a)
Lag
b)
Lead
c)
Lag-lead
d)
Zero
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Machine Experts answered |
Lag compensator:
Transfer function:
Transfer function:
If it is in the form of 
then a < 1
then a < 1If it is in the form of 
then a > b
Maximum phase lag frequency:
ωm = 1√Ta
Maximum phase lag::
then a > bMaximum phase lag frequency:
ωm = 1√Ta
Maximum phase lag::
ϕm is negative
Pole zero plot:
The pole is nearer to the origin.
Filter: It is a low pass filter (LPF)
Effect on the system:
Filter: It is a low pass filter (LPF)
Effect on the system:
- Rise time and settling time increases and Bandwidth decreases
- The transient response becomes slower
- The steady-state response is improved
- Stability decreases
An R-C network has the transfer function
The network could be used as
1. lead compensator
2. lag compensator
3. lag-lead compensator
Which of the above is/are correct?- a)1 only
- b)2 only
- c)3 only
- d)1, 2 and 3
Correct answer is option 'C'. Can you explain this answer?
An R-C network has the transfer function
The network could be used as
1. lead compensator
2. lag compensator
3. lag-lead compensator
Which of the above is/are correct?
The network could be used as
1. lead compensator
2. lag compensator
3. lag-lead compensator
Which of the above is/are correct?
a)
1 only
b)
2 only
c)
3 only
d)
1, 2 and 3
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Machine Experts answered |
Application:
Poles: s = -2, -8
Zeros: s = -4, -6
The pole-zero plot of the above transfer function is shown below.
The above pole-zero represents that the given system is a lag-lead compensator.
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Ranjith M
asked a question
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(Q.8 –Q.10) Consider the amplifier circuit shown below. The transistor is specified to have Vt = 0.4 V, kn = 0.4 mA/V2, W/L = 10 and λ = 0. Also, let VDD = 1.8V, RD = 17.5kΩ, VGS = 0.6V and vgs = 0V.
Q. Find ID.- a) 0.08 mA
- b) 0.16 mA
- c)0.4 mA
- d) 0.8 mA
Correct answer is option 'A'. Can you explain this answer?
(Q.8 –Q.10) Consider the amplifier circuit shown below. The transistor is specified to have Vt = 0.4 V, kn = 0.4 mA/V2, W/L = 10 and λ = 0. Also, let VDD = 1.8V, RD = 17.5kΩ, VGS = 0.6V and vgs = 0V.
Q. Find ID.
Q. Find ID.
a)
0.08 mA
b)
0.16 mA
c)
0.4 mA
d)
0.8 mA
The maximum phase shift that can be obtained by using a lead compensator with transfer function Gc(s) = 
equal to- a)15°
- b)30°
- c)45°
- d)60°
Correct answer is option 'B'. Can you explain this answer?
The maximum phase shift that can be obtained by using a lead compensator with transfer function Gc(s) = equal to
equal toa)
15°
b)
30°
c)
45°
d)
60°
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Cstoppers Instructors answered |
The standard T/F of the compensator is
Maximum phase lead
Maximum phase lead frequency,
ωm = 1/T√a
Calculation:
The given transfer function is,
By comparing both transfer functions,
aT = 0.15
T = 0.05
a = 3
Maximum phase lead
Maximum phase lead
Maximum phase lead frequency,
ωm = 1/T√a
Calculation:
The given transfer function is,
By comparing both transfer functions,
aT = 0.15
T = 0.05
a = 3
Maximum phase lead
= sin-1 (0.5)
ϕm = 30°
Given a badly underdamped control system, the type of cascade compensator to be used to improve its damping is- a)phase-lag
- b)phase-lead-lag
- c)phase-lead
- d)notch filter
Correct answer is option 'C'. Can you explain this answer?
Given a badly underdamped control system, the type of cascade compensator to be used to improve its damping is
a)
phase-lag
b)
phase-lead-lag
c)
phase-lead
d)
notch filter
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Cstoppers Instructors answered |
Phase Lead Compensator:
- A lead compensator provides a positive phase shift for increasing the value of frequencies from 0 to ∞.
- It is also known as a differentiator circuit.
- For a lead network, zero is nearer to the origin.
- It is used to improve the transient response of the system.
- It increases the damping of the system.
Phase Lag Compensator:
- A lead compensator provides a negative phase shift for increasing the value of frequencies from 0 to ∞.
- It is also known as an integrator circuit.
- For a lag network, pole is nearer to the origin.
- It is used to improve the steady state response of the system.
- It decreases the steady-state error of the system.
Which of the following is true for the network shown below -
- a)Lead compensator
- b)Lag compensator
- c)Lead-lag compensator
- d)None of the above
Correct answer is option 'A'. Can you explain this answer?
Which of the following is true for the network shown below -
a)
Lead compensator
b)
Lag compensator
c)
Lead-lag compensator
d)
None of the above
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Cstoppers Instructors answered |
In general, the lead and lag compensator is represented by the below transfer function
If a > b then that is lag compensator because pole comes first.
If a < b then that is the lead compensator since zero comes first.
Analysis:
Lead compensator:
1) When sinusoidal input applied to this it produces sinusoidal output with the phase lead input.
2) It speeds up the Transient response and increases the margin for stability.
A circuit diagram is as shown:
Response is:
Lead constant α =
A system with impulse response is essentially a _______ compensator and used as a ________ filter.- a)Integral, Comb
- b)Lead, high-pass
- c)Lag, low-pass
- d)Proportional, all pass
Correct answer is option 'C'. Can you explain this answer?
A system with impulse response is essentially a _______ compensator and used as a ________ filter.
a)
Integral, Comb
b)
Lead, high-pass
c)
Lag, low-pass
d)
Proportional, all pass
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Cstoppers Instructors answered |
Lag compensator:
Transfer function:
Transfer function:
If it is in the form of 
then a < 1
If it is in the form of
then a > b
Maximum phase lag frequency: ωm = 1/T√α
Maximum phase lag: ϕm = sin−1(a−1/a+1)
ϕm is negative
then a < 1If it is in the form of
then a > bMaximum phase lag frequency: ωm = 1/T√α
Maximum phase lag: ϕm = sin−1(a−1/a+1)
ϕm is negative
Pole zero plot:
The pole is nearer to the origin.
Filter: It is a low pass filter (LPF)
Effect on the system:
Filter: It is a low pass filter (LPF)
Effect on the system:
- Rise time and settling time increases and Bandwidth decreases
- The transient response becomes slower
- The steady-state response is improved
- Stability decreases
Which one of the following gives the V - I characteristic of an ideal voltage source?- a)
- b)
- c)
- d)
Correct answer is option 'C'. Can you explain this answer?
Which one of the following gives the V - I characteristic of an ideal voltage source?
a)
b)
c)
d)
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Constructing Careers answered |
- In every practical voltage source, there is some electrical resistance inside it. This resistance is called the internal resistance of the source.
- When the terminal of the source is open-circuited, there is no current flowing through it; hence there is no voltage drop inside the source but when the load is connected with the source, current starts flowing through the load as well as the source itself.
- But in an ideal voltage source, this difference is considered as zero that means there would not be any voltage drop in it when current flows through it and this implies that the internal resistance of an ideal source must be zero.
This can be concluded that voltage across the source remains constant for all values of load current.
The V-I characteristics of an ideal voltage source are shown below.
Ideal case with noise effect,
Considering the effect of noise, Ideal Voltage Source delivers constant voltage irrespective of the value of current through it and V-I characteristics are given as:
Ideal case with noise effect,
Considering the effect of noise, Ideal Voltage Source delivers constant voltage irrespective of the value of current through it and V-I characteristics are given as:
The ideal current source will have- a)high internal resistance
- b)zero internal resistance
- c)an infinite internal resistance
- d)low internal resistance
Correct answer is option 'C'. Can you explain this answer?
The ideal current source will have
a)
high internal resistance
b)
zero internal resistance
c)
an infinite internal resistance
d)
low internal resistance
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Constructing Careers answered |
Ideal Current Source: An ideal current source has infinite resistance. Infinite resistance is equivalent to zero conductance. So, an ideal current source has zero conductance.
Practical Current Source: A practical current source is equivalent to an ideal current source in parallel with a high resistance or low conductance.
Ideal and practical current sources are represented as shown the below figure.
Which one of the following must be ensured when two batteries are connected in parallel?- a)They should have the same make
- b)They should have the same emf
- c)They should have the same internal resistance
- d)They should have the same ampere-hour capacity
Correct answer is option 'B'. Can you explain this answer?
Which one of the following must be ensured when two batteries are connected in parallel?
a)
They should have the same make
b)
They should have the same emf
c)
They should have the same internal resistance
d)
They should have the same ampere-hour capacity
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Constructing Careers answered |
When batteries are connected in parallel it must be ensured that they have the same emf to avoid short circuits and to avoid any circulating current between batteries..
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Vikash Parashar
asked a question
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A microprocessor with a 16-bit address bus is used in a linear memory selection configuration (i.e., Address bus lines are directly used as chip selects of memory chips) with 4 memory chips. The maximum addressable memory space is- a)64 K
- b)16 K
- c)8 K
- d)4 K
Correct answer is option 'A'. Can you explain this answer?
A microprocessor with a 16-bit address bus is used in a linear memory selection configuration (i.e., Address bus lines are directly used as chip selects of memory chips) with 4 memory chips. The maximum addressable memory space is
a)
64 K
b)
16 K
c)
8 K
d)
4 K
To neglect a voltage source, the terminal across the source are-- a)Open circuited
- b)Short circuited
- c)Replace by inductor
- d)Replace by some resistance
Correct answer is option 'B'. Can you explain this answer?
To neglect a voltage source, the terminal across the source are-
a)
Open circuited
b)
Short circuited
c)
Replace by inductor
d)
Replace by some resistance
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Constructing Careers answered |
To neglect a voltage source, the terminal across the sources are short-circuited. Because ideally, the internal resistance of the voltage source is zero.
To neglect a current source, the terminal across the sources are open-circuited. Because ideally, the internal resistance of the current source is infinite.
Identify the source that has the following symbol.
- a)Current-controlled voltage source
- b)Voltage-controlled voltage source
- c)Voltage-controlled current source
- d)Current-controlled current source
Correct answer is option 'C'. Can you explain this answer?
Identify the source that has the following symbol.
a)
Current-controlled voltage source
b)
Voltage-controlled voltage source
c)
Voltage-controlled current source
d)
Current-controlled current source
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Gate Gurus answered |
Concept:
Independent sources:
An independent voltage source maintains a voltage (fixed or varying with time) which is not affected by any other quantity. Similarly, an independent current source maintains a current (fixed or time-varying) which is unaffected by any other quantity.
An independent voltage source maintains a voltage (fixed or varying with time) which is not affected by any other quantity. Similarly, an independent current source maintains a current (fixed or time-varying) which is unaffected by any other quantity.
Dependent sources:
- Some voltage (current) sources have their voltage (current) values varying with some other variables.
- They are called dependent (voltage or current) sources or controlled (voltage or current) sources.
- It is represented in diamond symbol.
- Since the control of the dependent source is achieved by a voltage or current of some other element in the circuit, and the source can be voltage or current.
- It follows that there are four possible types of dependent sources, namely:
(i) Voltage-controlled voltage source (VCVS)
(ii) Current-controlled voltage source (CCVS)
(iii) Current-controlled current source (CCCS)
(iv) Voltage-controlled current source (VCCS)
An ideal current source should have- a)Zero internal resistance
- b)Infinite internal resistance
- c)Large value of e.m.f.
- d)e.m.f.
Correct answer is option 'B'. Can you explain this answer?
An ideal current source should have
a)
Zero internal resistance
b)
Infinite internal resistance
c)
Large value of e.m.f.
d)
e.m.f.
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Gate Gurus answered |
Ideal voltage source: An ideal voltage source have zero internal resistance.
Practical voltage source: A practical voltage source consists of an ideal voltage source (VS) in series with internal resistance (RS) as follows.
An ideal voltage source and a practical voltage source can be represented as shown in the figure.
Practical voltage source: A practical voltage source consists of an ideal voltage source (VS) in series with internal resistance (RS) as follows.
An ideal voltage source and a practical voltage source can be represented as shown in the figure.
Ideal current source: An ideal current source has infinite resistance. Infinite resistance is equivalent to zero conductance. So, an ideal current source has zero conductance.
Practical current source: A practical current source is equivalent to an ideal current source in parallel with high resistance or low conductance.
Ideal and practical current sources are represented as shown in the below figure.
A non-ideal current source of 25 mA is supplying a resistive load of 5 kΩ. If the actual current flowing through the load is 20 mA, then the internal resistance of the source is:- a)1 kΩ
- b)10 kΩ
- c)5 kΩ
- d)20 kΩ
Correct answer is option 'D'. Can you explain this answer?
A non-ideal current source of 25 mA is supplying a resistive load of 5 kΩ. If the actual current flowing through the load is 20 mA, then the internal resistance of the source is:
a)
1 kΩ
b)
10 kΩ
c)
5 kΩ
d)
20 kΩ
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Machine Experts answered |
Concept:
Ideal Current Source: An ideal current source has infinite resistance. Infinite resistance is equivalent to zero conductance. So, an ideal current source has zero conductance.
Practical Current Source: A practical current source is equivalent to an ideal current source in parallel with high resistance or low conductance.
Ideal and practical current sources are represented as shown in the below figure.
Practical Current Source: A practical current source is equivalent to an ideal current source in parallel with high resistance or low conductance.
Ideal and practical current sources are represented as shown in the below figure.
Calculation:
Resistive load RL = 5 × 103 Ω
Current through load IL= 20 × 10-3 A
Internal resistance = r
Voltage across load, VL = RL × IL
= 5 × 103 × 20 × 10-3
= 100 V
The net current through internal resistance
r = 25 mA - 20 mA = 5 mA
Voltage across internal resistance = current × r
100 = 5 × 10-3 × r
r = 20 kΩ
Current through load IL= 20 × 10-3 A
Internal resistance = r
Voltage across load, VL = RL × IL
= 5 × 103 × 20 × 10-3
= 100 V
The net current through internal resistance
r = 25 mA - 20 mA = 5 mA
Voltage across internal resistance = current × r
100 = 5 × 10-3 × r
r = 20 kΩ
If an ideal voltage source and ideal current source are connected in series, the combination- a)Has the same properties as a current source alone
- b)Has the same properties as a voltage source alone
- c)Has the some properties as the source which has a higher value
- d)Results in the branch being redundant
Correct answer is option 'A'. Can you explain this answer?
If an ideal voltage source and ideal current source are connected in series, the combination
a)
Has the same properties as a current source alone
b)
Has the same properties as a voltage source alone
c)
Has the some properties as the source which has a higher value
d)
Results in the branch being redundant
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Gate Gurus answered |
Concept:
Ideal voltage source: An ideal voltage source have zero internal resistance.
Practical voltage source: A practical voltage source consists of an ideal voltage source (VS) in series with internal resistance (RS) as follows.
An ideal voltage source and a practical voltage source can be represented as shown in the figure.
... morePractical voltage source: A practical voltage source consists of an ideal voltage source (VS) in series with internal resistance (RS) as follows.
An ideal voltage source and a practical voltage source can be represented as shown in the figure.
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Biswajeet Soren
asked a question
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A modulated signal is given by,s(t) = m1(t) cos (2 π fct) + m2(t) sin (2 π fct)where the baseband signal m1(t) and m2(t) have bandwidths of 10 kHz and 15 kHz respectively. The bandwidth of the modulated signal, in kHz, is- a)10
- b)15
- c)25
- d)30
Correct answer is option 'D'. Can you explain this answer?
A modulated signal is given by,
s(t) = m1(t) cos (2 π fct) + m2(t) sin (2 π fct)
where the baseband signal m1(t) and m2(t) have bandwidths of 10 kHz and 15 kHz respectively. The bandwidth of the modulated signal, in kHz, is
a)
10
b)
15
c)
25
d)
30
The Norton theorem reduces a circuit to which of the following circuits? - a)A current source only
- b)A current source with an impedance in parallel
- c)A current source with an impedance in series
- d)A voltage source only
Correct answer is option 'B'. Can you explain this answer?
The Norton theorem reduces a circuit to which of the following circuits?
a)
A current source only
b)
A current source with an impedance in parallel
c)
A current source with an impedance in series
d)
A voltage source only
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Gate Gurus answered |
Norton’s Theorem:
Any two terminal bilateral linear DC circuits can be replaced by an equivalent circuit consisting of a current source and a parallel resistor.
In which constant voltage system following operations are performed: - Measure the system current
- Compare it with a reference current
- Computes and amplifies the error signal
- a)Constant extinction angle δ control
- b)Constant voltage control
- c)Constant lignition angle β control
- d)Constant current control
Correct answer is option 'D'. Can you explain this answer?
In which constant voltage system following operations are performed:
- Measure the system current
- Compare it with a reference current
- Computes and amplifies the error signal
a)
Constant extinction angle δ control
b)
Constant voltage control
c)
Constant lignition angle β control
d)
Constant current control
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Gate Gurus answered |
Constant Current Control:
- This method of current control regulates the current by adjusting the duty cycle to maintain a constant output current regardless of changes to the input voltage and output resistance.
- A power supply operating in constant current mode will compare its reference against the scaled output current. This can be accomplished through the use of a hall effect sensor, a shunt with a differential amplifier, or any other current to voltage conversion method.
- The process of comparing the reference against the scaled output current generates an error signal which is then amplified.
The formula for energy stored in the mechanical system of linear motion type is ______- a)1/2 Jwr2
- b)1/2 mv2
- c)1/2 mv
- d)Jwr2
Correct answer is option 'B'. Can you explain this answer?
The formula for energy stored in the mechanical system of linear motion type is ______
a)
1/2 Jwr2
b)
1/2 mv2
c)
1/2 mv
d)
Jwr2
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Gate Funda answered |
Energy stored is kinetic energy, since the system is of linear motion.
What is the coupling field used between the electrical and mechanical systems in energy conversion devices?- a)Magnetic field
- b)Electric field
- c)Magnetic field or Electric field
- d)None of the mentioned
Correct answer is option 'C'. Can you explain this answer?
What is the coupling field used between the electrical and mechanical systems in energy conversion devices?
a)
Magnetic field
b)
Electric field
c)
Magnetic field or Electric field
d)
None of the mentioned
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EduRev GATE answered |
Either electric field or magnetic field can be used, however most commonly we use magnetic field because of its greater energy storage capacity.
In an electro-mechanical energy conversion device, which of the following statements are correct regarding the coupling field?
(i) electrical side is associated with emf and current
(ii) electrical side is associated with torque and speed
(iii) mechanical side is associated with emf and current
(iv) mechanical side is associated with torque and speed- a)(i) & (ii)
- b)(ii) & (iii)
- c)(iii) & (iv)
- d)(i) and (iv)
Correct answer is option 'D'. Can you explain this answer?
In an electro-mechanical energy conversion device, which of the following statements are correct regarding the coupling field?
(i) electrical side is associated with emf and current
(ii) electrical side is associated with torque and speed
(iii) mechanical side is associated with emf and current
(iv) mechanical side is associated with torque and speed
(i) electrical side is associated with emf and current
(ii) electrical side is associated with torque and speed
(iii) mechanical side is associated with emf and current
(iv) mechanical side is associated with torque and speed
a)
(i) & (ii)
b)
(ii) & (iii)
c)
(iii) & (iv)
d)
(i) and (iv)
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Gate Funda answered |
The coupling field will be associated with the electrical quantities on electrical side and vice versa.
The energy storing capacity of magnetic field is about ________ times greater than that of electric field.- a)50,000
- b)25,000
- c)10,000
- d)40,000
Correct answer is option 'B'. Can you explain this answer?
The energy storing capacity of magnetic field is about ________ times greater than that of electric field.
a)
50,000
b)
25,000
c)
10,000
d)
40,000
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EduRev GATE answered |
As the energy storage capacity of the magnetic field is higher, it is most commonly used as coupling medium in electro-mechanical energy conversion devices.
The open loop transfer function of a unity gain negative feedback system is given as
The Nyquist contour in the ��-plane encloses the entire right half plane and a small neighbourhood around the origin in the left half plane, as shown in the figure below. The number of encirclements of the point (−1 + j0) by the Nyquist plot of G(s), corresponding to the Nyquist contour, is denoted as N. Then N equals to
- a)0
- b)1
- c)2
- d)3
Correct answer is option 'B'. Can you explain this answer?
The open loop transfer function of a unity gain negative feedback system is given as
The Nyquist contour in the ��-plane encloses the entire right half plane and a small neighbourhood around the origin in the left half plane, as shown in the figure below. The number of encirclements of the point (−1 + j0) by the Nyquist plot of G(s), corresponding to the Nyquist contour, is denoted as N. Then N equals to
The Nyquist contour in the ��-plane encloses the entire right half plane and a small neighbourhood around the origin in the left half plane, as shown in the figure below. The number of encirclements of the point (−1 + j0) by the Nyquist plot of G(s), corresponding to the Nyquist contour, is denoted as N. Then N equals to
a)
0
b)
1
c)
2
d)
3
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Constructing Careers answered |
Concept
N = P - 2
N = no. of encirclements of )-1, 0) critical point by the Nyquist plot.
P = no. of right half of s-plane of G(s) H(s) as F(s)
z = no. of lright half of s-plane of CLTF as zero of F(s)
For stability z = 0
N - P = 0
N = P
for Nyquist stability criteria
Calculation
Open loop function:
Close loop transfer function =
Close loop transfer function =
no pole in right hand side
z = 0, P ⇒ 1
N = 1 - 0
N = 1
no. of oncirclements N = 1
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Rachika Grewal
asked a question
|
An ac voltage of 220 V is applied to a pure inductance of 50 H. If the current is 5 A, the instantaneous value of voltage and current will be respectively given by- a)v= 622 sin (314t) Volts
i = 7.07 cos (314t-90°) Amps - b)v= 311 sin (314t) Volts
i = 14 .14 sin (314t - 90°) Amps - c)v= 311 sin (314t) Volts
i = 7.07 sin (314t - 90°) Amps - d)v=622 sin (314t) Volts
i = 14.14 cos (314 t - 90°) Amps
Correct answer is option 'C'. Can you explain this answer?
An ac voltage of 220 V is applied to a pure inductance of 50 H. If the current is 5 A, the instantaneous value of voltage and current will be respectively given by
a)
v= 622 sin (314t) Volts
i = 7.07 cos (314t-90°) Amps
i = 7.07 cos (314t-90°) Amps
b)
v= 311 sin (314t) Volts
i = 14 .14 sin (314t - 90°) Amps
i = 14 .14 sin (314t - 90°) Amps
c)
v= 311 sin (314t) Volts
i = 7.07 sin (314t - 90°) Amps
i = 7.07 sin (314t - 90°) Amps
d)
v=622 sin (314t) Volts
i = 14.14 cos (314 t - 90°) Amps
i = 14.14 cos (314 t - 90°) Amps
Consider a closed-loop control system with unity negative feedback and KG(s) in the forward path, where the gain K = 2. The complete Nyquist plot of the transfer function G(s) is shown in the figure. Note that the Nyquist contour has been chosen to have the clockwise sense. Assume G(s) has no poles on the closed right-half of the complex plane. The number of poles of the closed-loop transfer function in the closed right-half of the complex plane is ___________.
- a)0
- b)1
- c)2
- d)3
Correct answer is option 'B'. Can you explain this answer?
Consider a closed-loop control system with unity negative feedback and KG(s) in the forward path, where the gain K = 2. The complete Nyquist plot of the transfer function G(s) is shown in the figure. Note that the Nyquist contour has been chosen to have the clockwise sense. Assume G(s) has no poles on the closed right-half of the complex plane. The number of poles of the closed-loop transfer function in the closed right-half of the complex plane is ___________.
a)
0
b)
1
c)
2
d)
3
|
|
Constructing Careers answered |
Concept:
Nyquist stability criterion:
N = P – Z
N is the number of encirclements of (-1+j0) point by the Nyquist contour in an anticlockwise direction.
P is the open-loop RHP poles
Z is the closed-loop RHP poles
Analysis:
For K = 1,
For K = 2, the plot will be
For K = 2, the plot will be
N = No. of encirclement about (-1, 0) in anticlockwise.
P = Total number of open loop poles, in R.H.S.
Z = P - N
N = -2, P = 0
Z = 0 - (-2) = 2
Z = 2
Two poles in right side.
The figure shows the Nyquist plot of the open-loop transfer function G(s)H(s) of a system. If G(s)H(s) has one right-hand pole, the closed-loop system is
- a)Always stable
- b)Unstable with one closed - loop right hand pole
- c)Unstable with two closed - loop right hand poles
- d)Unstable with three closed - loop right hand poles
Correct answer is option 'A'. Can you explain this answer?
The figure shows the Nyquist plot of the open-loop transfer function G(s)H(s) of a system. If G(s)H(s) has one right-hand pole, the closed-loop system is
a)
Always stable
b)
Unstable with one closed - loop right hand pole
c)
Unstable with two closed - loop right hand poles
d)
Unstable with three closed - loop right hand poles
|
|
Cstoppers Instructors answered |
Concept:
The stability from the Nyquist plot is given by:
N = P - Z
where N = No. of encirclement of the critical point -1+j0 in an anticlockwise direction
P = No. of open-loop poles
Z = No. of zeroes of the characteristic equation
For a system to be stable, the value of Z = 0.
Calculation:
Given, P = 1
From the figure, N =1
N = P - Z
1 = 1 - Z
Z = 0
Hence, the system is stable.
If the Nyquist plot cuts the negative real axis at a distance of 0.8, then the gain margin of the system is- a)−0.8
- b)2.25
- c)0.8
- d)1.25
Correct answer is option 'D'. Can you explain this answer?
If the Nyquist plot cuts the negative real axis at a distance of 0.8, then the gain margin of the system is
a)
−0.8
b)
2.25
c)
0.8
d)
1.25
|
|
Cstoppers Instructors answered |
Concept:
The gain margin is defined as the amount of change in open-loop gain needed to make a closed-loop system unstable.
where, |G| = Gain of the system
ωpc = Phase crossover frequency
The frequency at which the gain of the system is zero is known as the phase crossover frequency.
Calculation:
GM = 1/0.8
GM = 1.25
The gain margin is defined as the amount of change in open-loop gain needed to make a closed-loop system unstable.
where, |G| = Gain of the system
ωpc = Phase crossover frequency
The frequency at which the gain of the system is zero is known as the phase crossover frequency.
Calculation:
GM = 1/0.8
GM = 1.25
The frequency at which the Nyquist plot of a unity feedback system with the open loop transfer function
crosses the negative real axis is- a)1 rad / s
- b)√2 rad / s
- c)√3 rad / s
- d)5 rad / s
Correct answer is option 'C'. Can you explain this answer?
The frequency at which the Nyquist plot of a unity feedback system with the open loop transfer function crosses the negative real axis is
crosses the negative real axis isa)
1 rad / s
b)
√2 rad / s
c)
√3 rad / s
d)
5 rad / s
|
|
Cstoppers Instructors answered |
Concept:
- Nyquist plot crosses the negative real axis at phase cross over frequency (ωpc)
- The phase crossover frequency is the frequency at which the phase angle first reaches −180°
- i.e., ∠(G(ωpc)) = -1800
Calculation:
Given G(s) =
∠(G(ωpc)) = 900 – 0.5 tan-1(ωpc) – 4 tan-1(ωpc) = -1800
By solving we get ωpc = √3 rad/sec
∠(G(ωpc)) = 900 – 0.5 tan-1(ωpc) – 4 tan-1(ωpc) = -1800
By solving we get ωpc = √3 rad/sec
In Nyquist plot of a system on adding a pole at s = 0, then plot will -- a)remain unaltered
- b)rotate clockwise by 90°
- c)rotate anticlockwise by 90°
- d)rotate by 180°
Correct answer is option 'B'. Can you explain this answer?
In Nyquist plot of a system on adding a pole at s = 0, then plot will -
a)
remain unaltered
b)
rotate clockwise by 90°
c)
rotate anticlockwise by 90°
d)
rotate by 180°
|
|
Gate Gurus answered |
Due to adding a pole at s = 0, the angle of shifting in the Nyquist plot of the system will be a shift of 90° clockwise.
Due to adding a zero at s = 0, the angle of shifting in the Nyquist plot of the system will be a shift of 90° anti-clockwise.
The shapes of the Nyquist plot for different transfer functions are given below:
The number and direction of encirclements around the point −1+j0 in the complex plane by the Nyquist plot of 
- a)zero.
- b)one, anti-clockwise.
- c)one, clockwise.
- d)two, clockwise.
Correct answer is option 'A'. Can you explain this answer?
The number and direction of encirclements around the point −1+j0 in the complex plane by the Nyquist plot of
a)
zero.
b)
one, anti-clockwise.
c)
one, clockwise.
d)
two, clockwise.
|
|
Machine Experts answered |
Concept:
The Nyquist plot is equal to the polar plot & mirror Image of the polar plot with respect to the real axis, with opposite direction + semicircle of the infinite radius in a clockwise direction as many as the type of system.
Calculation:
Given:
So,
Polar plot of Given G(s) is
So,
Polar plot of Given G(s) is
Now,
Nyquist plot of Given G(s) is:
Hence, the number of Encirclements of (-1 + j0) = 0
Nyquist plot of Given G(s) is:
Hence, the number of Encirclements of (-1 + j0) = 0
|
Swetha Kunduru
asked a question
|
For Bode plot of (1 + jωT) has- a)slope of 20 dB/decade and phase angle + tan-1 (ωT)
- b)slope of - 20 dB/decade and phase angle + tan-1 (ωT)
- c)slope of 20 dB/decade and phase angle - tan-1 (ωT)
- d)slope of - 40 dB/decade and phase angle - tan-1(ωT)
Correct answer is option 'A'. Can you explain this answer?
For Bode plot of (1 + jωT) has
a)
slope of 20 dB/decade and phase angle + tan-1 (ωT)
b)
slope of - 20 dB/decade and phase angle + tan-1 (ωT)
c)
slope of 20 dB/decade and phase angle - tan-1 (ωT)
d)
slope of - 40 dB/decade and phase angle - tan-1(ωT)
The most important technique used for stability and the transient response of the system is- a)Nyquist plot
- b)Root locus
- c)Bode plot
- d)Routh Hurwitz criteria
Correct answer is option 'B'. Can you explain this answer?
The most important technique used for stability and the transient response of the system is
a)
Nyquist plot
b)
Root locus
c)
Bode plot
d)
Routh Hurwitz criteria
|
|
Machine Experts answered |
Definition:
The root locus plots the poles of the closed-loop transfer function in the complex s-plane as K varies from 0 to ∞
The purpose of Root locus is defined as:
- To find the nature of the system and ‘K’ value for stability.
- To find the relative stability.
- If the root locus branches move towards the right, system is less stable and if they move towards the left then the system is more relative stable.
- It is the best method to find the Relative stability and RH criteria is best to find absolute stability
The relation between the closed-loop and open-loop poles
D(s) = 0 gives open-loop poles and N(s) = 0 gives closed-loop poles
Characteristic equation is D(s) + kN(s) = 0.
Closed-loop poles are nothing but the sum of open-loop poles and zeroes.
A single-input single-output feedback system has forward transfer function G(s) and feedback transfer function H(s). It is given that |G(s)H(s)| < 1. Which of the following is true about the stability of the system?- a)The system is always stable
- b)The system is stable if all zeros of G(s)H(s) are in left half of the s-plane
- c)The system is stable if all poles of G(s)H(s) are in left half of the s-plane
- d)It is not possible to say whether or not the system is stable from the information given
Correct answer is option 'C'. Can you explain this answer?
A single-input single-output feedback system has forward transfer function G(s) and feedback transfer function H(s). It is given that |G(s)H(s)| < 1. Which of the following is true about the stability of the system?
a)
The system is always stable
b)
The system is stable if all zeros of G(s)H(s) are in left half of the s-plane
c)
The system is stable if all poles of G(s)H(s) are in left half of the s-plane
d)
It is not possible to say whether or not the system is stable from the information given
|
|
Machine Experts answered |
Concept:
D(s) = 1 + G(s)H(s)
D(s) = 1 + G(s)H(s)
D(s) gives the roots of characteristic equation i.e. closed-loop poles.
Nyquist stability criteria state that the number of unstable closed-loop poles is equal to the number of unstable open-loop poles plus the number of encirclements of the origin of the Nyquist plot of the complex function D(s).
It can be slightly simplified if instead of plotting the function D(s) = 1 + G(s)H(s), we plot only the function G(s)H(s) around the point and count encirclement of the Nyquist plot of around the point (-1, j0).
From the principal of argument theorem, the number of encirclements about (-1, j0) is
N = P - Z
Where
Where P = Number of open-loop poles on the right half of s plane
Z = Number of closed-loop poles on the right half of s plane
Calculation:
For the given system, we have |G(s)H(s)| < 1
So, we may easily conclude that the Nyquist-plot intersect the negative real axis between 0 and -1 point, i.e. the Nyquist plot does not enclose the point (-1, 0) or in other words number of encirclements is zero.
⇒ N = 0
For a stable closed loop system, we must have Z = 0.
To get Z = 0, from the Nyquist criteria, P must be equal to zero.
Therefore, the system is stable if all poles of G(s)H(s) are in left half of the s-plane.
From the below given Nyquist plot, calculate the number of open-loop poles on the right-hand side of the s-plane for the closed-loop system to be stable.
- a)1
- b)2
- c)0
- d)-1
Correct answer is option 'A'. Can you explain this answer?
From the below given Nyquist plot, calculate the number of open-loop poles on the right-hand side of the s-plane for the closed-loop system to be stable.
a)
1
b)
2
c)
0
d)
-1
|
|
Machine Experts answered |
Principle arguments
- It states that if there are “P” poles and “Z” zeroes for a closed, random selected path then the corresponding G(s)H(s) plane encircles the origin with P – Z times.
- Encirclements in s – plane and GH – plane are shown below.
- In GH plane Anti clockwise encirclements are taken as positive and clockwise encirclements are taken as negative.
An electro-mechanical energy conversion device is one which converts _______- a)Electrical energy to mechanical energy only
- b)Mechanical energy to electrical energy only
- c)Electrical to mechanical and mechanical to electrical
- d)None of the mentioned
Correct answer is option 'C'. Can you explain this answer?
An electro-mechanical energy conversion device is one which converts _______
a)
Electrical energy to mechanical energy only
b)
Mechanical energy to electrical energy only
c)
Electrical to mechanical and mechanical to electrical
d)
None of the mentioned
|
|
Constructing Careers answered |
The operating principles of electrical to mechanical and mechanical to electrical conversion devices are similar, hence, the common name electro-mechanical device. However, their structural details differ depending on their function.
Singly and doubly excited magnetic systems applications are respectively ________- a)loud speakers and tachometers
- b)synchronous motors and moving iron instruments
- c)DC shunt machines and solenoids
- d)reluctance motors and synchronous motors
Correct answer is option 'D'. Can you explain this answer?
Singly and doubly excited magnetic systems applications are respectively ________
a)
loud speakers and tachometers
b)
synchronous motors and moving iron instruments
c)
DC shunt machines and solenoids
d)
reluctance motors and synchronous motors
|
|
Gate Gurus answered |
Reluctance motors can work on single excitation, and synchronous motors require double excitation.
Which components of torque in the following equation are called the reluctance torque terms?
Te = 1/2is2dLs/dθr + 1/2ir2dLr/dθr+isirdMsr/dθr- a)1/2is2dLs/dθr and isirdMsr/dθr
- b)1/2is2dLs/dθr and 1/2ir2dLr/dθr
- c)1/2ir2dLr/dθr and isirdMsr/dθr
- d)1/2is2dLs/dθr, 1/2ir2dLr/dθr and isirdMsr/dθr
Correct answer is option 'B'. Can you explain this answer?
Which components of torque in the following equation are called the reluctance torque terms?
Te = 1/2is2dLs/dθr + 1/2ir2dLr/dθr+isirdMsr/dθr
Te = 1/2is2dLs/dθr + 1/2ir2dLr/dθr+isirdMsr/dθr
a)
1/2is2dLs/dθr and isirdMsr/dθr
b)
1/2is2dLs/dθr and 1/2ir2dLr/dθr
c)
1/2ir2dLr/dθr and isirdMsr/dθr
d)
1/2is2dLs/dθr, 1/2ir2dLr/dθr and isirdMsr/dθr
|
|
EduRev GATE answered |
Because the change of reluctance (Rls or Rlr) are responsible for the production of these torques.
|
Anjali Mishra
asked a question
|
Consider a simple mass spring friction system as given in the figure K1, K2 are spring constants f-friction, M-Mass, F-Force, x-Displacement. The transfer function X(s)/F(s) of the given system will be :
- a)1/(Ms2+fs+K1.K2)
- b)1/(Ms2+fs+K1+K2)
- c)1/(Ms2+fs+K1.K2/K1+K2)
- d)K2/(Ms2+fs+K1)
Correct answer is option 'B'. Can you explain this answer?
Consider a simple mass spring friction system as given in the figure K1, K2 are spring constants f-friction, M-Mass, F-Force, x-Displacement. The transfer function X(s)/F(s) of the given system will be :
a)
1/(Ms2+fs+K1.K2)
b)
1/(Ms2+fs+K1+K2)
c)
1/(Ms2+fs+K1.K2/K1+K2)
d)
K2/(Ms2+fs+K1)
In a doubly excited magnetic system of salient pole type stator and rotor, the reluctance torque is present only when _________- a)both stator and rotor currents are acting
- b)stator current is acting alone
- c)rotor current is acting alone
- d)any of the stator or rotor currents acting alone
Correct answer is option 'D'. Can you explain this answer?
In a doubly excited magnetic system of salient pole type stator and rotor, the reluctance torque is present only when _________
a)
both stator and rotor currents are acting
b)
stator current is acting alone
c)
rotor current is acting alone
d)
any of the stator or rotor currents acting alone
|
|
EduRev GATE answered |
Equation for magnetic torque is Te = 1/2is2dLs/dθr+1/2ir2dLr/dθr+isirdMsr/dθr, if ir = 0, Te = 1/2is2dLs/dθr and if is = 0, then Te = 1/2ir2dLr/dθr, and these equations for torque are called reluctance torques.
|
Taranhaar Kumar
asked a question
|
Voltage remaining constant, if the frequency is increased then- a)eddy current losses will decrease
- b)hysteresis loss will decrease
- c)eddy current losses will remain unchanged
- d)hysteresis losses will remain unchanged
Correct answer is option 'C'. Can you explain this answer?
Voltage remaining constant, if the frequency is increased then
a)
eddy current losses will decrease
b)
hysteresis loss will decrease
c)
eddy current losses will remain unchanged
d)
hysteresis losses will remain unchanged
In a doubly excited magnetic system of salient pole stator and rotor, the magnetic torque (Te) depends on which of the following statements?
(i) the instantaneous values of currents is and ir
(ii) the angular rate of change of inductances
(iii) the differential changes of current dis and dir
(iv) only the instantaneous values of self inductance- a)(i), (iii)
- b)(i), (ii)
- c)(iii), (iv)
- d)(i), (iv)
Correct answer is option 'B'. Can you explain this answer?
In a doubly excited magnetic system of salient pole stator and rotor, the magnetic torque (Te) depends on which of the following statements?
(i) the instantaneous values of currents is and ir
(ii) the angular rate of change of inductances
(iii) the differential changes of current dis and dir
(iv) only the instantaneous values of self inductance
(i) the instantaneous values of currents is and ir
(ii) the angular rate of change of inductances
(iii) the differential changes of current dis and dir
(iv) only the instantaneous values of self inductance
a)
(i), (iii)
b)
(i), (ii)
c)
(iii), (iv)
d)
(i), (iv)
|
|
Gate Funda answered |
Te = 1/2 is 2dLs/dθr + 1/2ir2dLr/dθr + isirdMsr/dθr.
Which of the following statements are true about electromagnetic torques and reluctance torques?
(i) electromagnetic torque can exist only if both windings carry current
(ii) reluctance torque depend on the direction of current in stator or rotor windings
(iii) reluctance torque doesn't depend on the direction of current in stator or rotor windings
(iv) electromagnetic torque depend on the direction of currents is and ir
(v) electromagnetic torque doesn't depend on the direction of currents is and ir- a)(i), (ii), (iii)
- b)(ii), (iii), (v)
- c)(i), (iii), (iv)
- d)(ii), (iii), (iv)
Correct answer is option 'C'. Can you explain this answer?
Which of the following statements are true about electromagnetic torques and reluctance torques?
(i) electromagnetic torque can exist only if both windings carry current
(ii) reluctance torque depend on the direction of current in stator or rotor windings
(iii) reluctance torque doesn't depend on the direction of current in stator or rotor windings
(iv) electromagnetic torque depend on the direction of currents is and ir
(v) electromagnetic torque doesn't depend on the direction of currents is and ir
(i) electromagnetic torque can exist only if both windings carry current
(ii) reluctance torque depend on the direction of current in stator or rotor windings
(iii) reluctance torque doesn't depend on the direction of current in stator or rotor windings
(iv) electromagnetic torque depend on the direction of currents is and ir
(v) electromagnetic torque doesn't depend on the direction of currents is and ir
a)
(i), (ii), (iii)
b)
(ii), (iii), (v)
c)
(i), (iii), (iv)
d)
(ii), (iii), (iv)
|
|
Gate Funda answered |
Reluctance torque:
1/2is2dLs/dθr and 1/2ir2dLr/dθr
Positive or negative value of current doesn’t affect the torque direction. The interaction/electromagnetic torque = isirdMsr/dθr, here the direction of is and ir changes the torque.
1/2is2dLs/dθr and 1/2ir2dLr/dθr
Positive or negative value of current doesn’t affect the torque direction. The interaction/electromagnetic torque = isirdMsr/dθr, here the direction of is and ir changes the torque.
|
Sunil Manjani
asked a question
|
The Hartley-Shannon theorem sets a limit on the- a)highest frequency that may be sent over a given channel
- b)maximum capacity of channel with a given noise level
- c)maximum number of coding levels in a channel with a given noise level
- d)maximum number of quantizing levels in a channel with a given noise level
Correct answer is option 'B'. Can you explain this answer?
The Hartley-Shannon theorem sets a limit on the
a)
highest frequency that may be sent over a given channel
b)
maximum capacity of channel with a given noise level
c)
maximum number of coding levels in a channel with a given noise level
d)
maximum number of quantizing levels in a channel with a given noise level
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