KR Series Non-Flammable Wire Wound Resistors
Construction — Wire wound resistive element in a non-flammable ceramic housing
Power ratings — 120W, 200W, 300W, 400W, 500W, and 600W
Resistance range — 0.02Ω to 20Ω
Tolerance — ±10%
Temperature coefficient of resistance — 400ppm/°C maximum
Insulation resistance — 20MΩ minimum
Mounting — Chassis or panel mount with terminal connections
What are the KR Series Non-Flammable Wire Wound Resistors?
The KR is a range of high-power wire wound resistors designed for heavy-duty power dissipation in industrial equipment where safety and long-term structural integrity under sustained thermal load are paramount. The defining characteristic of the series is its non-flammable housing, which encases the wire wound resistive element in a ceramic body that will not ignite or sustain combustion even under fault conditions or prolonged overloading. This property makes the KR series suitable for installation inside enclosed panels, cabinets, and equipment housings where the use of a component that could act as an ignition source would be unacceptable under safety regulations or insurance requirements.
Power ratings span from 120W to 600W, placing the KR series firmly in the high-power dissipation bracket and distinguishing it from the lower-rated ceramic encased families in the RQB, RQL, and AQL series. The resistance range of 0.02Ω to 20Ω is deliberately narrow and concentrated at the low end of the ohmic scale, reflecting the series’ primary function as a high-current, low-resistance power dissipation element rather than a general-purpose resistance component. At these low values and high power ratings, the KR is suited to carrying large continuous or pulsed currents while limiting voltage across the element to a manageable level. Tolerance is ±10%, which is consistent with the series’ role in power dissipation and braking duties where exact resistance values are less critical than thermal robustness and current-carrying capacity.
The temperature coefficient of resistance is specified at 400ppm/°C maximum, acknowledging that at high continuous dissipation levels the element will operate at elevated temperatures and that some resistance drift with temperature is inherent to the wire wound construction at this power level. The insulation resistance of 20MΩ minimum ensures adequate electrical isolation between the resistive element and the chassis or mounting hardware, confirming suitability for line-voltage industrial environments. The combination of a non-flammable ceramic enclosure, low resistance range, high power rating, and robust wire wound construction makes the KR a reliable long-life component for sustained power dissipation duties where safety compliance and structural durability are the primary design requirements.
KR Series Non-Flammable Wire Wound Resistors Specifications
A practical overview for engineers and procurement teams evaluating resistive solutions.
Model: KR
Resistor type: Wire wound
Description: Non-flammable
Power Rating: 120W~600W
Resistance (Ω): 0.2~20
Tolerance (%): ±10
TCR (ppm/C): 400 max.
Applications of the KR Series Non-Flammable Wire Wound Resistors
Where RARA wire wound resistors are deployed in the field.
The KR series is suited to high-power industrial applications requiring non-flammable resistors in the 120W to 600W range at low resistance values. Primary uses include dynamic braking resistors in variable speed motor drives and crane hoist drives, where kinetic energy recovered during deceleration must be dissipated as heat safely within the drive enclosure.
Discharge resistors in large DC bus capacitor banks in inverters, converters, and UPS systems, where rapid and reliable energy removal on shutdown is required; current-limiting and inrush protection resistors in high-current AC and DC industrial circuits; load resistors in generator and alternator load testing equipment, where continuous high-power dissipation over extended test periods is required; and neutral grounding and earthing resistors in medium-voltage distribution and industrial power systems where low-resistance, high-power elements must perform reliably over decades of service.
The non-flammable ceramic enclosure also makes the KR well suited to safety-critical installations in rail traction systems, mining equipment, offshore and marine power panels, and any enclosed industrial environment where component combustibility is subject to regulatory or certification requirements.
Related Products of the KR Series Non-Flammable Wire Wound Resistors
Model: EWS
Resistor type: Wire wound
Description: Edge wound
Power Rating: 400W~1600W
Resistance (Ω): 0.02~1
Tolerance (%): ±5, ±10
TCR (ppm/C): 800 max.
Model: EW
Resistor type: Wire wound
Description: Edge wound assembly
Power Rating: 3kW~12kW
Resistance (Ω): 0.05~48
Tolerance (%): ±5, ±10
TCR (ppm/C): 800 max.
Model: DBR
Resistor type: Wire wound
Description: Dynamic braking
Power Rating: 8kW~60kW
Resistance (Ω): 1~150
Tolerance (%): ±5, ±10
TCR (ppm/C): 800 max.
Model: RLB
Resistor type: Wire wound
Description: Load bank
Power Rating: 50kW~3000kW
Resistance (Ω): 0.1~1M
Tolerance (%): ±5, ±10
TCR (ppm/C): 200
Why Choose RARA Wire Wound Resistors
What sets RARA apart for engineers and procurement managers in industrial and automotive markets.
01
Widest Design Range
From 0.5W precision types to 12kW edge wound assemblies — one wire wound product family covering precision, ceramic-encased, fusible, non-flammable, and high-power variants.
02
Precision Available
The PWR series delivers ±0.1% tolerance and TCR as low as 20 ppm/°C — precision wire wound performance for instrumentation and measurement circuits.
03
Automotive Qualified
The AQL ceramic-encased series is AEC-Q200 qualified for automotive-grade reliability in EV battery management, HVAC, and powertrain applications.
04
Global Track Record
Trusted by Siemens, Rockwell, Toshiba, Schneider Electric, LG, and Hanwha — a customer base built on decades of consistent, certified performance.
