A phase or polyphase disconnect in a metering circuit, but not all phases lose voltage.
2. What is phase failure protection?
A protective device that relies on the disappearance of an electric current in a phase conductor of a multiphase circuit, or a phase or several phase voltage loss of a multiphase system to prevent the power supply from being applied to a protected device.
3. What is a circuit break?
When the circuit does not have a closed switch, or the wires are not connected properly, or if the appliance is burned out or not installed (e.g., the voltmeter is connected in series with the circuit), the whole circuit is disconnected somewhere.
4. Definition of under voltage and over voltage
For all the electrical equipments, they have a rated voltage, but in practice, it cannot guarantee to work under rated voltage. It actually works at a range of ±15% of the rated voltage. If the voltage is less than -15%, it is "under voltage"". If the voltage is higher than +15%, it is "overvoltage"".
5. Difference between under voltage protection and over voltage protection
Under voltage protection: when the line voltage drops to a certain value, the motor can automatically switch off from the power supply. It’s a protection to avoid the motor running under undervoltage.
Overvoltage protection: a mode of protection that disconnects the power supply or reduces the voltage of the controlled equipment when the voltage exceeds the predetermined maximum value.
6. Loss of voltage and loss of voltage protection
Loss of voltage: when the power supply fails or for some reason, the voltage of the power supply decreases too much, it is called "loss of voltage"".
Loss of voltage protection: when the circuit is lower than the rated voltage or power failure, the corresponding protection effect is obtained. After voltage loss, it is necessary to restart the circuit to operate again to avoid accidents.