BC1 Series Rheostat Variable Power Wirewound Resistors
High-power wirewound rheostat variable resistor, operable as a two-terminal rheostat (varistor) or three-terminal potentiometer
Power ratings of 12.5W, 25W, 50W, 100W, and 150W in single units; scalable up to 3000W by connecting up to six 500W units in series or parallel
Resistance range 0.5Ω to 1kΩ at 12.5W; 0.5Ω to 3.3kΩ at 25W and 50W; 1.5Ω to 4.7kΩ at 100W; 1.5Ω to 5.1kΩ at 150W
Resistance tolerance ±5% (J) and ±10% (K)
Temperature coefficient of resistance (TCR) ±200 to ±400 ppm/°C
Dielectric withstand voltage 1kV to 10kV AC for 60 seconds with leakage current limit of 2.5mA
Insulation resistance 50 to 1000MΩ at 1000V DC
Short-time overload capability: 5 times rated power for 10 seconds; 10 times rated power for 5 seconds; 25 times rated power for 1 second
Load life rated at 500 hours under continuous duty cycle (90 minutes on, 30 minutes off) at rated voltage
Vibration resistance qualified at 1.5mm amplitude, 10Hz to 55Hz
Low and high temperature storage qualification at −55°C and +70°C respectively
Non-flammable construction confirmed at 10 times rated power for 5 minutes
What are the BC1 Series Rheostat Variable Power Wirewound Resistors?
The BC1 is a high-power wirewound rheostat variable resistor designed for applications requiring continuously adjustable resistance under substantial power dissipation. Unlike the precision wirewound potentiometers in the DM, DOW, and DG series, which are optimised for accuracy and signal-level operation, the BC1 is built for power-level service: its wirewound element must handle significant current continuously, its construction must withstand repeated mechanical adjustment under load, and its insulation system must tolerate voltages from 1kV up to 10kV AC. The BC1 can be connected as a two-terminal rheostat, presenting a variable resistance between the wiper and one end terminal, or as a three-terminal potentiometer with independent access to both end terminals and the wiper.
Five single-unit power ratings are offered — 12.5W, 25W, 50W, 100W, and 150W — each with a corresponding resistance range matched to the current-handling capacity of the wirewound element at that power level. For applications requiring higher total power dissipation, up to six 500W units can be connected in series or parallel to build assemblies from 500W through to 3000W in 500W steps, providing a scalable high-power variable resistance solution from a single product family without requiring custom-designed components. This multi-unit configurability is a defining feature of the BC1, enabling it to serve as the core adjustable element in high-power load banks, drive systems, and industrial machinery across a very wide power range.
The electrical durability specifications reflect the BC1’s industrial service role. The rated load test confirms resistance stability within ±(3% R + 0.1Ω) after one hour at rated voltage and 40°C. Short-time overload capability extends to 25 times rated power for one second, accommodating the surge currents common in motor starting, load switching, and fault-clearance events without permanent resistance shift. The load life test of 500 hours at rated voltage under a 90-minutes-on, 30-minutes-off duty cycle demonstrates endurance under sustained industrial operating conditions. The dielectric withstand voltage range of 1kV to 10kV AC, combined with an insulation resistance of 50 to 1000MΩ at 1000V DC, confirms suitability for high-voltage industrial environments. Non-flammability is verified at 10 times rated power for 5 minutes without combustion, an important safety qualification for equipment in enclosed industrial panels.
The TCR of ±200 to ±400 ppm/°C is characteristic of wirewound construction at power levels, where the priority is current-handling capacity and mechanical robustness rather than the tight temperature tracking of precision-grade wirewound types. Resistance tolerance is ±5% (grade J) or ±10% (grade K). Vibration resistance is qualified at 1.5mm amplitude across 10Hz to 55Hz, covering the mechanical stress environments typical of industrial machinery installations. Storage and operational temperature qualification spans −55°C to +70°C.
BC1 Series Rheostat Variable Power Wirewound Resistors Specifications
A practical overview for engineers and procurement teams evaluating resistive solutions.
Model: BC1
Resistor type: Variable
Description: Variable power rheostat
Power Rating: 12.5W~150W
Resistance (Ω): 0.5~5.1k
Tolerance (%): ±5, ±10
TCR (ppm/C): 200~400
Applications of the BC1 Series Rheostat Variable Power Wirewound Resistors
Where RARA variable resistors are deployed in the field.
Electric motor speed control — armature and field resistance adjustment in DC motor drive circuits for fans, blenders, mixers, and power tools
Industrial machinery RPM adjustment — variable resistance speed control in production line, conveyor, and process machinery drives
Load simulation and load banks — adjustable resistive loads for generator, UPS, and power supply testing and commissioning
Voltage and current adjustment — series resistance control in power circuits requiring stepless output adjustment
Educational and laboratory modelling — variable power resistance elements in electrical engineering demonstration and training equipment
High-power starting resistors — motor soft-start and current-limiting resistance in industrial AC and DC drive systems
Heating element control — variable series resistance for power adjustment in resistive heating applications
Automated control installations — field-adjustable resistance elements in process control and instrumentation systems
High-voltage test equipment — adjustable resistance in dielectric test sets and high-voltage laboratory equipment, exploiting the 1kV to 10kV dielectric withstand rating
Scalable high-power dissipation assemblies — multi-unit configurations of up to six 500W rheostats in series or parallel for load banks and drive systems requiring up to 3000W of adjustable power dissipation
Related Products of the BC1 Series Rheostat Variable Power Wirewound Resistors
Model: CN-15
Resistor type: Variable
Description: 15mm, trimming cermet potentiometer
Power Rating: 1W
Resistance (Ω): E6, 100~4.7M
Tolerance (%): ±20, ±30
TCR (ppm/C): 300
Model: PR-16
Resistor type: Variable
Description: 16mm, carbon single turn potentiometer
Power Rating: 0.1W
Resistance (Ω): E3, 100~10k
Tolerance (%): ±5, ±10, ±20, ±30
Model: PR-18
Resistor type: Variable
Description: 18.5mm, carbon single turn potentiometer
Power Rating: 0.2W
Resistance (Ω): E3, 120~2.2M
Tolerance (%): ±5, ±10, ±20, ±30
Model: PR-24
Resistor type: Variable
Description: 24mm, carbon single turn potentiometer
Power Rating: 0.5W
Resistance (Ω): E3, 100~1M
Tolerance (%): ±5, ±10, ±20, ±30
Why Choose RARA Variable Resistors
What sets RARA apart for engineers and procurement managers in industrial and automotive markets.
01
Full Spectrum Coverage
From 0.1W carbon signal potentiometers to 3000W industrial wire wound rheostats — RARA covers the complete variable resistor spectrum from a single ISO 9001 certified supplier.
02
Hermetic Sealed Options
PC-199 and CW-18 hermetically sealed cermet models resist moisture, dust, and contamination — extending service life in outdoor, marine, and industrial environments where standard potentiometers degrade rapidly.
03
Precision Wire Wound
DM, DOW, and DG precision wire wound potentiometers deliver the accuracy and repeatability needed for calibration, instrumentation, and closed-loop feedback applications.
04
Global Track Record
Trusted by Siemens, Rockwell, Schneider Electric, and Hanwha — deployed in industrial control and power regulation systems across six continents.
