Dependable Overload and Phase-Loss Protection for Medium and Heavy Three-Phase Motors
The Potric LR2D Thermal Overload Relay monitors motor current and trips the control circuit when the motor draws too much current for too long. This prevents overheating, extends motor life, and avoids costly burn-outs on pumps, compressors, fans, and industrial machinery.
Covering 23A to 65A, this range is built for higher-power motors. It is available in a standard size and a large size, so you can match the relay to the motor and to the space in your starter panel.
Key Features
- Four current ranges: 23-32A, 30-40A, 37-50A, and 48-65A, with overlapping ranges so you can pick the closest fit to your motor.
- Adjustable setting dial: set the trip current within the selected range.
- Phase-loss protection: trips quickly if one phase is lost.
- Class 10A trip characteristic: suited to standard motor starting conditions.
- 1NO + 1NC auxiliary contacts: use the NC contact in the control circuit and the NO contact for fault signalling.
- Test and reset functions: check operation and restore the relay after a trip.
- Standard and large sizes: choose the frame that suits your load and installation.
How to Choose the Right Range and Size
Select the range that contains your motor's rated current (from the motor nameplate), ideally with the rated current near the middle of the range. Then set the dial to the nameplate current.
- (23-32)A: available in standard and large size, for medium motors and pumps.
- (30-40)A and (37-50)A: for larger pumps, compressors, and machinery.
- (48-65)A: for heavy motors and industrial loads.
Always confirm the relay size is compatible with your contactor and wiring, as specified by a qualified electrician.
Typical Applications
- Large water pumps and booster stations
- Air compressors and refrigeration compressors
- Industrial fans, blowers, and ventilation systems
- Conveyors, crushers, mixers, and workshop machinery
- Motor starter panels and control cabinets
Important Note
An overload relay protects the motor against sustained overload. It does not protect against short circuit. Always install it together with a suitable short-circuit protection device, such as a motor circuit breaker or fuses, and a contactor.
Frequently Asked Questions
What is the difference between the standard and large size?
The large size is a bigger frame used for higher current ranges. The standard size is available in the 23-32A range. Check the variant you select before ordering.
How do I set the current?
Turn the dial to the full-load current shown on the motor nameplate.
What is the difference between an overload relay and a circuit breaker?
An overload relay protects the motor from sustained overcurrent and trips the contactor. A circuit breaker protects the wiring from short circuits and large faults. A motor circuit needs both.
What does phase-loss protection do?
If one phase is lost, the motor draws extra current and overheats. The relay detects this and trips quickly.
Do I need an electrician to install it?
Yes. Installation must be carried out by a qualified electrician in line with local regulations.
About Potric
Potric supplies dependable electrical protection and control products designed for everyday safety and long service life.