Motor protection relays for every application

Edited by the Engineeringtalk editorial team Sep 6, 2002

Crouzet has a complete range of electronic motor protection relays that provide protection against a range of faults, which if left undetected, could cause permanent damage to an electric motor.

Crouzet is now able to supply a complete range of high performance, electronic motor protection relays that provide accurate and reliable protection against a range of faults, which if left undetected, could cause permanent damage to an electric motor.

While the standard thermal overload relay, contactor and switch fuse combination provides 'general' protection, there are many situations where more accurate protection is necessary to protect personnel or machinery.

The range comprises Crouzet EIL, EIH or EIT relays to monitor overcurrent and undercurrent, EWS relays for phase sequence and loss of phase, EUL, EUH or EUS over/under voltage relays and ETM thermal protection relays.

They are compact, robust and easy to mount to a standard 35mm DIN rail.

Suitable for use on new installations or retrofit, Crouzet motor protection relays enable the motor protection characteristics to be matched to the demands of the application.

They can be used individually or together to provide a high level of protection.

For example, phase sequence and under/over voltage relays are ideal for use on portable and temporary installations.

Overcurrent causes many motors failures and Crouzet current monitoring relays are available in three ratings - EIL series from 2 to 500mA, EIH from 0.1 to 10A and EIT from 10 to 100A.

All are suitable for voltages from 24 to 230V and will detect overcurrent conditions caused by, for example, a blocked pump, jammed fan, seized bearing or simply attempting to exceed the capabilities of a machine.

The relay will also detect undercurrent conditions usually caused by the load being disconnected from the machine as a result of, for example, a mechanical failure such as a broken drive belt.

They can be tailored to the characteristics of the load using adjustments that include under and over current trip threshold, start up delay and running trip delay.

The relay trips in the event of an undercurrent/overcurrent situation, using electronic sensing to provide very accurate protection.

By tailoring the protection, the motor is provided with close protection against faults while allowing 'normal' events to be accommodated.

Other products in the range include the EWS phase monitoring and sequence relay for portable or mobile equipment, such as refrigerated vehicles or outside broadcast trailers, and the ETM thermistor relay for applications where the loading varies so greatly that the only reliable way to protect the motor is using a temperature sensing device embedded in the motor windings.

These applications typically include walkways and escalators.

The EUL, EUH and EUS voltage monitoring relays can be adjusted to trip when the voltage falls below or exceeds pre set values.

Typical applications include installations at sporting events, fairs and exhibitions, and machinery at remote locations - such as water pumping stations.

Easy to configure and adjust, Crouzet motor protection relays are simply connected into the control circuit of the contactor controlling the motor.

On detection of a fault condition, the relay contacts interrupt the supply to the contactor coil, disconnecting the supply to the motor.

To assist customers with the selection of the most suitable motor protection relay for their application, the Crouzet website provides the user with a datasheet for each of the relay types.

This includes technical details, list price and product code for ordering purposes.