WRM-10P, 10A Max Current, 1 Micro Ohm Range

The unit’s dual resistance-reading input channels can measure two winding resistances simultaneously, and four-wire (Kelvin) connections provide high accuracy and require no lead compensation. The WRM-10P provides stable resistance readings of very large transformers by utilizing a 36 VDC power supply capable of providing up to 10 A test current. The resistance reading of a 100 MVA transformer can be achieved in 5 minutes or less. The unit’s power supply is cooled by heavy-duty fans designed for continuous operation.  

Since the WRM-10P can accurately measure resistances ranging from 1 micro Ohm to 2000 Ohms, it can also be used to measure EHV circuit breaker contact resistance, motor winding resistance, or any low resistance. If the transformer winding temperature is entered, the WRM-10P can calculate the equivalent resistance value of the winding material (aluminum or copper) at any standard reference temperature. Also, a special test mode can run a test for up to 45 minutes while saving resistance readings at one-minute intervals. In addition to measuring the resistance value, the WRM-10P also checks the “make-before- break” tap-switching sequences of voltage regulators and load tap changers.

The WRM-10P is furnished with three 50-foot test cables. Each test cable lead is terminated with a quick-disconnect test clip.

Internal Test Record Storage
The WRM-10P can store 63 test records (up to 48 readings per test record) in Flash EEPROM. Test records can be retrieved and printed on the built-in thermal printer or can be transferred to a PC via the RS-232C interface port. Windows ® -based software is provided with each WRM-10P that can be used to retrieve test records from the WRM-10P and can also be used to export records in Microsoft Excel format.

Built-in Safety Features
At the end of each test, the WRM-10P automatically dissipates the stored energy in the transformer. This discharge circuit will continue to work even if the supply voltage is lost. For added safety, the unit’s power supply is thermally protected from over-load damage.

User interface
The WRM-10P features a back-lit LCD screen (20 characters by 4 lines) that is viewable in both bright sunlight and low-light levels. A rugged, alpha-numeric, membrane keypad is used to control the unit.