Accurate Overload and Phase-Loss Protection for Three-Phase Motors
The Potric LR2D13 Electronic 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, fans, compressors, and conveyors.
Electronic sensing gives more stable and repeatable tripping than a simple bimetal element, with less drift across changing ambient temperatures. The relay also detects the loss of a phase, one of the most common causes of motor failure.
Key Features
- 11 current ranges: from 0.63A up to 25A, so the relay can be matched closely to the motor's rated current.
- Adjustable setting dial: set the trip current within the selected range.
- Phase-loss protection: trips quickly if a phase is lost.
- Class 10 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.
- Clear tripped indication: easy fault identification.
How to Choose the Right Range
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.
- (0.63-1)A to (2.5-4)A: small motors, fans, and small pumps.
- (4-6)A to (9-13)A: medium motors, water pumps, and compressors.
- (12-18)A and (17-25)A: larger motors and heavier industrial loads.
Typical Applications
- Water pumps and booster pumps
- Fans, blowers, and ventilation systems
- Air compressors and refrigeration compressors
- Conveyors, 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 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.
How do I set the current?
Turn the dial to the full-load current shown on the motor nameplate.
Can I use it on a single-phase motor?
This relay is designed for three-phase motors. For single-phase use, check with a qualified electrician.
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.