BSR / BSQ Series Slide-Type Variable Power Wirewound Resistors
High-power slide-type variable wirewound resistors in two variants: BSR (round-wire wound) and BSQ (ribwound), for high-power and high-current adjustable resistance applications
BSR power ratings: 200W, 400W, 500W, 1000W, and 1300W; resistance range 0.5Ω to 13kΩ depending on rating
BSQ power ratings: 300W, 600W, 750W, 1500W, and 2000W; optimised for lower ohmic ranges where high energy dissipation is required
Resistance tolerance ±10% (grade K)
Adjustable range 10% to 90% of full end resistance value; power rating is proportional to the adjusted resistance in circuit
Tubular ceramic former with copper-alloy or chromium-alloy wirewound resistance element
All stainless steel grids and terminals with welded construction
High-temperature insulation throughout; end-frames with gussets for added mechanical strength
Entire assembly coated with high-temperature non-flammable resin
Slotted mounting holes for easy panel installation
RoHS compliant and lead free
Enclosure-based construction accommodates multiple resistor combinations for high-power assemblies up to 2000W in a single unit
What are the BSR / BSQ Series Slide-Type Variable Power Wirewound Resistors?
The BSR and BSQ are slide-type variable power wirewound resistors designed for high-power and high-current applications where a continuously adjustable resistance must be set and maintained under sustained heavy-duty operating conditions. Unlike the rotary wirewound potentiometers in the BC1 range, which use a rotating shaft and wiper mechanism, the BSR and BSQ use a linear slide mechanism: a firm rotating adjustment point that travels directly along the surface of the wirewound resistance element, allowing the effective resistance in circuit to be set to any point within the adjustable range of 10% to 90% of the full end resistance value. This direct contact sliding mechanism is robust, simple to adjust under load, and well suited to the physical scale of these high-power components.
The two series differ in their wirewound construction and consequently in their resistance range optimisation. The BSR uses conventional round-wire winding on a tubular ceramic former, covering resistance values from 0.5Ω up to 13kΩ across the power range and suited to general-purpose high-power variable resistance applications. The BSQ uses ribwound construction — in which the resistance wire is wound in a ribbed or edge-wound profile — which achieves a higher cross-sectional wire area per unit length, making the BSQ particularly effective where very large currents must be dissipated in the lower ohmic ranges. For applications in the low-ohm, high-current region of the power envelope, the BSQ provides a more compact and thermally efficient solution than a conventional round-wound type of equivalent rating.
The physical construction of both series is built for durability in industrial environments. The resistance element is wound onto a tubular ceramic former using copper-alloy or chromium-alloy wire, providing excellent temperature stability and resistance to oxidation at the elevated operating temperatures generated by high-power dissipation. All grids and terminals are stainless steel, and the enclosure is welded rather than mechanically assembled, eliminating the risk of joint loosening under vibration or thermal cycling. End-frames are fitted with structural gussets for additional mechanical rigidity. The entire assembly is coated with a high-temperature non-flammable resin, providing both electrical insulation and physical protection against contamination, arc flash risk, and accidental contact. Slotted mounting holes on the enclosure base allow straightforward panel or rack installation and permit minor positional adjustment during fitting.
Power rating for the BSR and BSQ is specified at the full end resistance value with the full resistance in circuit, based on a 25°C free air rating. When the slide is set to an intermediate position, both the effective resistance and the rated power dissipation decrease proportionally: setting the slide to half resistance reduces the usable power rating by approximately half. This proportional derating relationship must be accounted for in circuit design to ensure the selected unit is not operated beyond its thermal limits at the intended intermediate resistance setting. The enclosure-based design accommodates combinations of resistor elements within a single housing, allowing the BSR and BSQ to be configured for a wide range of total resistance and power dissipation requirements within a compact, unified mechanical assembly.
BSR / BSQ Series Slide-Type Variable Power Wirewound Resistors Specifications
A practical overview for engineers and procurement teams evaluating resistive solutions.
Model: BSR/BSQ
Resistor type: Variable
Description: Slide type variable power resistor
Power Rating: 200W~2000W
Resistance (Ω): 0.5~200 max.
Tolerance (%): ±10
Applications of the BSR / BSQ Series Slide-Type Variable Power Wirewound Resistors
Where RARA variable resistors are deployed in the field.
Industrial motor speed and torque control — continuously adjustable armature and field resistance in DC motor drive circuits for heavy-duty industrial machinery
High-power load banks and load simulation — adjustable resistive loads for generator, UPS, transformer, and power supply testing and commissioning at power levels up to 2000W per unit
Electrolytic and electrochemical process control — current and power adjustment in plating, anodising, and electrolysis supply circuits requiring high-current, low-resistance variable elements
Resistance welding and spot welding equipment — current control and energy adjustment in resistance welding power circuits
High-current laboratory and test equipment — adjustable power resistors in electrical engineering test rigs, burn-in systems, and calibration facilities
Variable voltage and current power supplies — series resistance adjustment for output voltage and current control in heavy-duty bench and industrial power equipment
Crane, hoist, and lifting equipment drives — rotor resistance starting and speed control in wound-rotor induction motor drive systems
Railway and traction control systems — braking resistance and speed control adjustment in DC traction motor circuits
High-power heating and temperature control — variable series resistance for power adjustment in industrial resistive heating installations
General-purpose high-power variable resistance — wherever a slide-type wirewound resistor rated between 200W and 2000W with a robust stainless steel and ceramic construction and RoHS-compliant lead-free materials is required
Related Products of the BSR / BSQ Series Slide-Type 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.
