A pitot relay is a device used in electrical circuits for high-speed tripping. It is commonly used in protection systems to detect the flow of electric current and initiate a tripping action in case of an abnormal or fault condition. Let's explore the working principle and applications of a pitot relay in detail.

The working principle of a pitot relay is based on the Bernoulli's principle, which states that the pressure of a fluid decreases as its velocity increases. The relay consists of a small tube called a pitot tube, which is placed in the path of the electric current. When the current flows through the tube, it creates a pressure difference between the two ends of the tube.

Here's how a pitot relay works:

1. Pressure Sensing: The pitot tube is designed in such a way that one end is exposed to the electric current, while the other end is sealed. As the current flows through the tube, it generates a pressure difference between the exposed and sealed ends.

2. Pressure Measurement: The pressure difference is measured using a pressure sensor, typically a diaphragm or a bellows. The sensor converts the pressure difference into a mechanical displacement.

3. Tripping Mechanism: The mechanical displacement is then used to actuate a tripping mechanism. This mechanism can be a set of contacts that open or close depending on the displacement of the pressure sensor. In the case of a pitot relay, the tripping mechanism is designed to open the circuit and interrupt the current flow.

Applications of Pitot Relay:

1. High-Speed Tripping: The main application of a pitot relay is high-speed tripping in electrical protection systems. It is used to detect faults such as short circuits or overloads and initiate a rapid tripping action to isolate the faulty section of the circuit. This helps in preventing damage to the equipment and ensuring the safety of the electrical system.

2. Power System Protection: Pitot relays are commonly used in power systems, including transmission and distribution networks. They are installed in circuit breakers, switchgear, and other protective devices to provide fast and reliable tripping in case of faults.

3. Motor Protection: Pitot relays can also be used for motor protection. They can detect abnormal conditions such as excessive current or voltage imbalances and initiate tripping to prevent motor damage.

In conclusion, a pitot relay is a device used for high-speed tripping in electrical circuits. It operates based on the pressure difference generated by the electric current flowing through a pitot tube. The pressure difference is measured and used to actuate a tripping mechanism, which interrupts the current flow. Pitot relays are widely used in power systems and motor protection applications to provide fast and reliable fault detection and tripping.