Mica Wirewound Resistors
Crohm Series CWM mica wirewound resistor coils are designed for light-duty braking of variable-frequency drives, heating applications and various AC and DC load applications. Available resistance values range from 300 to 2000 ohms, with typical wattage ratings of 250 watts per coil.
Product catalogues
Design
A high-quality stainless resistor alloy is wound around a high-temperature mica body. The element is attached to the mica board with 10-24 hardware that also serves as the resistor terminals. The open design allows direct contact with ambient air for efficient cooling.
Specifications
| Resistance range | 300–2000 Ω |
| Typical power | 250 watts per coil |
| Voltage insulation | 1000 volts |
| Insulation resistance (dry) | 1000 MΩ minimum |
| Resistance tolerance | ± 10% standard; contact factory for lower tolerances |
| Coefficient of resistivity | ~5% increase at full operating temperature |
| Operating temperature | 375 °C rise above ambient |
| Ambient derating | 40 °C base; −10% @ 50 °C, −20% @ 80 °C, −30% @ 100 °C |
Ordering & part numbers
Part numbers use CWM followed by the resistance in ohms. For example, CWM1000 is a 1000 ohm, 250 watt resistor. See the catalogue for dimensions and standard part numbers.
Standard ratings
Representative standard part numbers. Non-standard resistance, wattage and current values are available — request a quote.
| Part No. | Resistance (Ω) |
|---|---|
| CWM300 | 300 |
| CWM400 | 400 |
| CWM500 | 500 |
| CWM600 | 600 |
| CWM700 | 700 |
| CWM800 | 800 |
| CWM900 | 900 |
| CWM1000 | 1000 |
| CWM1100 | 1100 |
| CWM1200 | 1200 |
| CWM1300 | 1300 |
| CWM1400 | 1400 |
| CWM1500 | 1500 |
| CWM1600 | 1600 |
| CWM1700 | 1700 |
| CWM1800 | 1800 |
| CWM1900 | 1900 |
| CWM2000 | 2000 |
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