The use of over load relays in circuits is to protect the circuit against over heating .
The use is to stop something from getting to many volts at once .its like a fuse or circuit breaker I'm a house
Advantages of MU Overload Relay -
Protection Device
Cost-effective
High Performance.
current relay are using for over current low state & high state.but potential relay are related to voltage.
Typically, when the coil voltage on a relay is decreased gradually, the relay "hold" will release at a certain voltage. This is usually defined as the Drop-out voltage (defined at some minimum value). Now, in the case of latching relay, the Drop-out voltage is called the Reset voltage.
ocr-over current relay(senses the over current in the circuits) efr-earth fault relay uvr-under voltage relay
A voltage monitor relay is in the circuit for one reason. It monitors the incoming voltage to the equipment that it is protecting usually on three phase control panels.The relay monitors the three incoming line voltages and in some relays the voltage to ground (wye connection). If the circuit the relay is protecting looses one of the voltage legs, the circuit will shut down until the problem is rectified. This usually happens if a fuse blows in one of the three phase voltage legs.It also monitors the level of voltage to the circuit. If the voltage drops due to a malfunction in the utility lines the relay will trip and take the protected circuit off line. The voltages can be set to trip at any under or over voltage usually by set point controls on the front of the voltage monitoring relay.
Actually safety devices of generator depends on the type of prime mover used in generator. The main safety devices in a DG Set is to control the over speed, to limit the fuel supply in case of emergency. It is regulated by the governor of the DG Sets. In external safety, over voltage & over current tripping relay i.e. associated with DG Sets control panel.
to be protect the motor and electrical equipments.some circuit provide to protect the motor.for exm.DOL starter, OLR to protect the motors....
current relay are using for over current low state & high state.but potential relay are related to voltage.
Time delay protective relays used in the power industry can be time over current or voltage, or definite time over / under voltage / over current.Definite time type relays use an over / under voltage / current element that picks up when voltage / current reach a specified level. When this picks up, a timer is started. If current / voltage stays above / below the pickup value for long enough to allow the timer to expire, the relay trip contacts are closed.Time over current elements use an inverse time - current curve to define speed of operation, so the more current is present, the faster the relay will operate.
For what? Both exist, and are used often.
A protective device that operates when voltage exceeds nominal by some set amount. These are often coupled with a timer.
if you have checked the voltage with a dvom then you need to verify that the power source at the fuel pump relay is correct, if it has the correct voltage pre-relay then your problem is post-relay. if the voltage is not correct pre-relay then simply trace and repair the power source. if the problem is post relay then check the output voltage directly at the relay, if voltage is good trace and repair line from relay to pump. if voltage is not correct then replace the fuel pump relay
Typically, when the coil voltage on a relay is decreased gradually, the relay "hold" will release at a certain voltage. This is usually defined as the Drop-out voltage (defined at some minimum value). Now, in the case of latching relay, the Drop-out voltage is called the Reset voltage.
ocr-over current relay(senses the over current in the circuits) efr-earth fault relay uvr-under voltage relay
Under voltage relay provides a signal (Contacts) when the supplied voltage drops below a preset value.
A voltage monitor relay is in the circuit for one reason. It monitors the incoming voltage to the equipment that it is protecting usually on three phase control panels.The relay monitors the three incoming line voltages and in some relays the voltage to ground (wye connection). If the circuit the relay is protecting looses one of the voltage legs, the circuit will shut down until the problem is rectified. This usually happens if a fuse blows in one of the three phase voltage legs.It also monitors the level of voltage to the circuit. If the voltage drops due to a malfunction in the utility lines the relay will trip and take the protected circuit off line. The voltages can be set to trip at any under or over voltage usually by set point controls on the front of the voltage monitoring relay.
The voltage for a potential relay will depend on the circuit that the relay is installed in. The relay can be made for low voltages (5v) to higher voltages (440.)
If it fits and has the same voltage & amp rating you can use the fuse/relay.