Three measuring channels and demagnetization in an 8 kg device
Transformer winding resistance meters
RMO-TW
Transformer winding ohmmeter
Winding resistance measurement, solved with the essentials.
Product overview
Three windings in a single measurement
The four models of the series — RMO10TW, RMO20TW, RMO30TW and RMO50TW — measure the winding resistance of inductive objects with ripple-free DC current and up to 55 V output, in a light metal housing of 8 to 8.5 kg. The three independent channels test primary, secondary and tertiary windings connected in series at once, and saturating the core through the winding with the most turns shortens stabilisation.
Tap changer verified, core demagnetized
Resistance is measured at every tap position — on-load or de-energized (DETC) — without discharging between taps, with interruption detection and a warning to the operator; when finished, the automatic demagnetization removes remanent magnetism.
Main features
- Range from 0.1 µΩ to 100 kΩ with ±(0.1% + 0.1%) accuracy.
- Best resolution of 0.1 µΩ.
- Tap changer verification with 4 ms sampling.
- Pt100 temperature channel for the Heat Run test.
- Automatic discharge circuit for the stored energy.
- Memory for 1000 measurements (5000 optional).
- Thermal and overcurrent protection; interference filtering.
Applications and software
Applications
- Windings of power and distribution transformers and autotransformers.
- Verification of on-load and de-energized tap changers.
- Motor and generator stators through the three channels.
- Non-inductive resistive objects: busbars, splices and joints.
- Heat Run test with resistance and temperature extrapolation.
PC software for control and analysis
The included PC software controls and observes the process over USB, saves and analyses the results, records the test current during tap changer transitions and assembles reports in Excel, PDF or Word, with the Heat Run calculations built in.
Light and to the point
At 8 kg for the 10 and 20 A models and 8.5 kg for the 30 and 50 A ones, the series travels with the maintenance crew without giving up power: the RMO50TW delivers 1000 W of output to stabilise large windings quickly.
| RMO-TW�—�MEASUREMENT�DATA | |
|---|---|
| Measuring range | 0.1 µΩ – 100 kΩ |
| Typical accuracy | ±(0.1% rdg + 0.1% FS) up to 1.999 kΩ; ±(0.2% + 0.1%) up to 9.999 kΩ; ±(1% + 1%) up to 100 kΩ |
| Resolution | From 0.1 µΩ (up to 999.9 µΩ) to 10 Ω (up to 99.99 kΩ), depending on the scale |
| Test current | 5 mA – 50 A DC depending on model; output voltage up to 55 V DC |
| Tap changer verification | 4 ms sampling; interruption detection |
| Temperature | 1 Pt100 class B channel; -50 to +180 °C; 0.1 °C resolution |
| Memory | 1000 positions (5000 optional) |
| Communication | USB; optional RS232 and Bluetooth |
Specifications valid at +25 °C with the standard accessories.
The manufacturer reserves the right to change the specifications without prior notice.
RMO-TW�—�TECHNICAL�SPECIFICATIONS
| RMO10TW | RMO20TW | RMO30TW | RMO50TW | |
|---|---|---|---|---|
| Test current | 5 mA – 10 A | 5 mA – 20 A | 5 mA – 30 A | 5 mA – 50 A |
| Output power | 500 W | 750 W | 850 W | 1000 W |
| Output voltage | Up to 55 V DC | Up to 55 V DC | Up to 55 V DC | Up to 55 V DC |
| Dimensions | 198 × 250 × 350 mm | 198 × 250 × 350 mm | 198 × 250 × 350 mm | 198 × 250 × 350 mm |
| Weight | 8 kg | 8 kg | 8.5 kg | 8.5 kg |
Common: consumption 2250 VA; supply 90 – 264 V AC, 50/60 Hz; backlit 4 × 20 character LCD; optional 58 mm thermal printer; IP40; operation -20 to +60 °C; storage -40 to +70 °C; humidity 0 – 95% non-condensing.
Standards: safety EN 61010-1; EMC EN 61326-1; overvoltage category II; pollution degree 2. Specifications valid at +25 °C.