Elementary tripping circuit for a circuit breaker

A simple and classic topic!

An elementary tripping circuit for a circuit breaker is a basic circuit that detects an overcurrent condition and trips the breaker to disconnect the power supply. Here's a simple example:

Tripping Circuit Components:

1. Current Transformer (CT): A CT is a device that produces a secondary current proportional to the primary current. In this case, it's used to sense the current flowing through the circuit.
2. Rectifier: A rectifier converts the AC current from the CT into a DC voltage.
3. Voltage Reference (VR): A VR provides a stable DC voltage reference.
4. Comparator: A comparator compares the DC voltage from the rectifier with the voltage reference.
5. Tripping Coil: A tripping coil is an electromagnet that, when energized, trips the circuit breaker.

Tripping Circuit Operation:

1. When the current flowing through the circuit exceeds a predetermined threshold, the CT produces a secondary current proportional to the primary current.
2. The secondary current is rectified by the rectifier, producing a DC voltage.
3. The DC voltage is compared with the voltage reference by the comparator.
4. If the DC voltage exceeds the voltage reference, the comparator outputs a high signal.
5. The high signal energizes the tripping coil, which trips the circuit breaker, disconnecting the power supply.

Tripping Circuit Schematic:

Here's a simple schematic representation of the tripping circuit:

          +---------------+
          |  Current    |
          |  Transformer  |
          |  (CT)        |
          +---------------+
                  |
                  |
                  v
          +---------------+
          |  Rectifier  |
          |  (DC output) |
          +---------------+
                  |
                  |
                  v
          +---------------+
          |  Voltage    |
          |  Reference  |
          |  (VR)       |
          +---------------+
                  |
                  |
                  v
          +---------------+
          |  Comparator  |
          |  (outputs high  |
          |   if DC voltage  |
          |   exceeds VR)  |
          +---------------+
                  |
                  |
                  v
          +---------------+
          |  Tripping Coil  |
          |  (trips circuit  |
          |   breaker)     |
          +---------------+

This is a basic tripping circuit, and there are many variations and improvements that can be made depending on the specific application and requirements.