Description
WRM-40 winding resistance meter
The WRM-40 is designed to accurately measure the winding resistance of highly inductive power transformers. 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-40 provides stable resistance readings of very large transformers by utilizing a 36Vdc power supply capable of outputting up to 40 Amperes. The resistance reading of a 500MVA transformer can be achieved in 5 minutes or less. The unit’s power supply is cooled by four heavy-duty fans designed for continuous operation. For greater flexibility in the field, the WRM-40 comes with a built-in 2.5-inch wide thermal printer used for printing test reports.
Since the WRM-40 can accurately measure resistances ranging from 1 microohm to 500 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-40 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-40 also checks the “make-be- fore-break” tap switching sequences of voltage regulators and load tap changers.
The WRM-40 can store test results in Flash EE- PROM. Test results can be printed on the built-in 2.5-inch wide thermal printer or can be transferred to a PC via the RS-232C interface port.
The WRM-40 is furnished with three 50-foot test cables. Each test cable lead is terminated with a quick-disconnect test clip.
Built-in Safety Features
At the end of each test, the WRM-40 automatically dissipates the stored energy in the trans- former. 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.
Internal Test Record Storage
The WRM-40 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. A Windows® -based application is provided with each WRM- 40 that can be used to retrieve test records from the WRM-40 and can also be used to export re- cords in Microsoft® Excel format.
User Interface
The WRM-40 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.
Built-in Thermal Printer
The WRM-40 features a built-in 2.5″ wide ther- mal printer that can be used to print test reports in the field.
Outstanding features
- Auto discharge circuit for operator safety
- Auto current ranging from 10 mA to 40 A
- Digital resistance reading from 1 micro- ohm to 500 ohms
- Stores 63 records (of 48 readings each)
- Built-in 2.5-inch wide thermal Printer
