Panel multifunctional digital motor protection relay | overload protection | phase imbalance | current and voltage monitoring | with external CT current transformers | AC 380V | 10-999A

The relay combines the main electric motor protection functions: overload, undercurrent, locked-rotor, high-current, phase-loss, current-imbalance, ground-fault, overvoltage and undervoltage monitoring. Motor current is monitored through external CT current transformers. Manual or automatic reset is available after certain faults.

Current is measured using CT current transformers installed separately from the main relay body. The monitored conductors are routed through the corresponding CTs, and their measurement signals are transmitted to the motor protection relay.

In definite-time mode, protection trips after the configured delay has elapsed. In inverse-time mode, the trip time depends on the magnitude of the overload – a greater overload generally results in a faster protection response.

The startup delay allows protection operation to be coordinated with the acceleration time of the specific motor. This is especially relevant for high-inertia fans, pumps, conveyors, compressors and other drives that are more difficult to start.

Although this function is described as short-circuit protection, the electronic relay control output is not a power switching device capable of interrupting short-circuit current. The motor power circuit must still use a correctly selected circuit breaker, fuses or motor protection circuit breaker with the required short-circuit breaking capacity.

If automatic reset is enabled, the motor control circuit may automatically become ready for restart after the fault condition disappears. For machinery where an unexpected restart could create a hazard to people or equipment, additional safety interlocking measures must be provided.

3A / 380V AC with a resistive load.

The relay's 10–999A range refers to the monitored motor current / protection setting range. Current is measured through external CT current transformers. The 3A / 380V AC output contacts are control contacts. The motor power circuit is normally switched through a separate contactor.

• Overload protection with definite-time or inverse-time characteristics.
• Undercurrent protection.
• Locked-rotor protection.
• Fast high-current monitoring with ≤50ms response.
• Current imbalance protection.
• Phase-loss protection.
• Ground-fault / leakage-current monitoring.
• Overvoltage protection.
• Undervoltage protection.
• Adjustable startup delay.
• Manual and automatic reset.

• Wide 10–999A protection range.
• External CT current transformers.
• Multiple protection functions in one device.
• Adjustable startup delay up to 200s.
• Dedicated locked-rotor protection.
• Fast high-current monitoring ≤50ms.
• 10–50% current imbalance monitoring.
• Phase-loss protection.
• Overvoltage and undervoltage monitoring.
• Automatic or manual reset.
• 1NO + 1NC output contacts.
• LED display.
• Panel-mounted, flush installation.

• Requires accurate configuration: incorrect current and timing settings may cause false or delayed protection operation.
• Correct CT connection is required: external current transformers must be installed and connected according to the manufacturer's wiring diagram.
• Panel mounting requires a suitable panel cut-out.
• Does not replace a short-circuit circuit breaker or fuses.
• The 3A / 380V AC contacts are intended for control, not for directly switching a 16A motor power circuit.
• Automatic reset should only be used after assessing the risk of unexpected motor restart.

The rated current of a pump motor is 32A. Motor current is monitored through external CT current transformers, while the appropriate overload-current setting and trip characteristic are configured in the motor protection relay according to the project requirements and motor data.

During startup, for example, a startup delay of several seconds can be used so that normal starting current is not incorrectly interpreted as a fault.

If the pump mechanism jams and the current rises to the configured locked-rotor protection threshold, after 3 seconds the relay changes the state of its output contacts and stops the motor through the contactor control circuit.

If the pump begins operating without load and the current falls below the configured threshold, undercurrent protection may trip.

At the same time, the device can monitor phase-current imbalance, phase loss, ground fault and supply-voltage limits.

This relay version is not designed for DIN-rail mounting. The main unit is installed flush into the electrical panel, while separate external CTs are used for current measurement.

The protection current range is 10-999A.

Motor current is measured using external CT current transformers.

The main relay unit is designed for panel-mounted, flush installation in the front section of an electrical or automation panel.

No. This version is intended for panel-mounted, flush installation.

380V AC, 50/60Hz.

Yes. Definite-time or inverse-time protection can be used.

Yes. A 0.5–60s delay is provided for this function.

Yes. The startup delay can be adjusted from 0 to 200 seconds.

Yes. The threshold is adjustable from 1.5 to 8 times the overload-current setting, with a 3s delay.

Yes. The threshold is adjustable from 10 to 50%, with a 5s operating delay.

Yes. The phase-loss delay is 2s.

Yes. The threshold is adjustable from 30mA to 2.5A, with a 1s delay.

No. If protection against electric shock is required by the project, a dedicated RCD / RCCB / RCBO must be used.

Yes. The adjustment range is 65–690V, with a 5s delay.

Yes. The adjustment range is 65–600V, with a 5s delay.

Yes. The reset time is adjustable from 0.1 to 30 minutes, and the number of attempts from 1 to 10.

Manual, automatic or power-cycle reset.

1NO + 1NC.

3A / 380V AC with a resistive load.

No. The relay contacts are intended for the control circuit; the motor power circuit should normally be switched by a contactor.

No. A correctly selected circuit breaker or fuses must be used for cable and short-circuit protection.

The relay and external CT current transformers must be installed and configured by a qualified electrical specialist. The CTs must be connected according to the manufacturer's wiring diagram for the specific device. Protection current, delay, voltage, current imbalance and automatic reset parameters must be selected according to the specific motor nameplate, starting characteristics, driven mechanism and project requirements.

The relay does not replace a correctly selected short-circuit protective device or power contactor. When automatic reset is used, the risk of unexpected motor restart must be assessed and all necessary mechanical and electrical safety interlocks must be provided.