C-Shaped Rheostat Power Variable Resistors


Introduction (FVR)

(FVR) Rheostats, power variable resistors control the speed of a motor.

Rheostat Power Variable Resistors (FVR)
Rheostats, Power Variable Resistor (FVR)
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Token's (FVR) Series is a C-shaped ceramic rod and wound with copper or chromium-alloy wire as a resistance element. Except for the slide contact surface, the entire component is coated with a high-temperature, non-flammable resin. After cooling and drying, insulation is applied through a high-temperature process. Then, a centered rotating adjuster component is installed, which slides along the resistance element and varies the resistance to the desired value.

Adjustable wirewound resistors are often called potentiometers in books and catalogues. Variable (FVR) may be used as a power rheostat with two connections (the wiper and just one end of the track) or as a potentiometer with all three connections in use.

Downloads Complete Specification in PDF C-Shaped Rheostat Power Variable Resistor (FVR).

Applications :

  1. Motor controller also use FVR Series as rheostats or potentiometer to control the speed of a motor by limiting the flow of current through them.
  2. They are used in many small appliances such as blenders, mixers, fans, and power tools.
  3. FVR Rheostats Series are also used as test instruments to provide an accurate resistance value.
  4. While FVR can be used to control electric ovens and cooktops, thermostats are preferred because they have additional parts which automatically adjust the current flow to maintain a constant temperature.

The scope of the application also includes educational modeling, load simulations, industrial machinery RPM adjustment, voltage and current adjustment, instruments, and automated control installations.

Features :

  1. Standard resistance tolerance is K(±10%). Closer tolerances are available upon request.
  2. 3 Wattage Rating styles to choose: 25W, 50W, and 100W.
  3. Wide Max. Resistance range: 5Ω ~ 5KΩ.

The FVR Series is RoHS compliant and lead free. For non-standard technical requirements and custom special applications, please contact us.

Dimensions (FVR 25W - 100W)

Top View (FVR) Dimensions
Top View (FVR) Dimensions
Side View (FVR) Dimensions
Side View (FVR) Dimensions
Bottom View (FVR) Dimensions
Bottom View (FVR) Dimensions
Dimensions(mm) Max. Pickable Resistance Value (Ω)
A B C D E F G H I J K Weight
25W 2.5 3.2 22 3/8" 6x12 42 50 50 11 5 10 74/g 5Ω-2.5KΩ
50W 4.2 4.2 28 3/8" 6x12 64 60 70 11 8 14 160/g 7Ω-3.5KΩ
100W 4.2 4.2 42 3/8" 6x12 85 75 90 11 8 14 372/g 10Ω-5KΩ

Application Notes (FVR)

Determination of End Resistance Value of FVR, DQS, DSRA, DSRB, BSR, BSQ:

  1. Resistance Range means you can choose one maximum resistance value (Max. Pickable Resistance / End resistance value)
    at one of FVR, DQS, DSRA, DSRB, BSR, BSQ VR (Variable Resistor) type.

  2. After End Resistance Value confirmed, the minimum resistance (start resistance value) will be determined
    by depending on resistance of wire and wirewound type.

Power Rating of Variable Resistor:
The part Nunber formation of FVR, DQS, DSRA, DSRB, BSR, BSQ:

Product type - Rated Wattage - Max. Pickable Resistance (Ω) - Resistance Tolerance

Product type means one of FVR, DQS, DSRA, DSRB, BSR, BSQ.
Rated Wattage means power rating at End Resistance Value.
Resistance Value (Ω) means maximum resistance value (End Resistance Value).
Resistance Tolerance means precision range of End Resistance Value.

1. Power Rating of VR (Variable Resistor) is determined by the maximum resistance value (End Resistance Value).
2. Resistance and Power Rating should be decreased while you are adjusting the screw.


  1. Adjustability is 10% to 90% of full resistance value.
  2. Wattage is proportional to this adjusted resistance value.

Power Rating:

  1. Based on 25°C free air rating. The stated wattage rating applies only when the entire resistance is in the circuit.
  2. Setting the lug at an intermediate point reduces the wattage rating by approximately the same proportion.
  3. Example: If the lug is set at half resistance, the wattage is reduced by approximately one-half.

If you need current constant type or special specifications, please feel free to cntact us.

Performance Specifications (FVR)

Test Item Test Methods Characteristics
Resistance tolerance JIS-C-5261 5-1 Resistance tolerance ±10%
Insulation resistance JIS-C-5261 6-1 500VDC 100MΩ min
Dielectric withstanding voltage JIS-C-5261 7-1 1000VDC 1 minute Between terminal and axis Free of appearance or structural irregularity
Terminal strength JIS-C-5261 6-5
3kg 30 seconds
Free of appearance or structural irregularity
ΔR/R≤ ±(2%+0.1Ω)
Vibration JIS-C-5261 6-6 1.5m/m 10 ~ 50 ~ 10 Hz/min X-Y-Z 2 hours each Free of appearance or structural irregularity
ΔR/R≤ ±(2%+0.1Ω)
Load life JIS-C-5261 7-7 Free of appearance or structural irregularity
ΔR/R≤ ±(5%+0.1Ω)
Full gyration angle JIS-C-5261 6-1 300± 5°C
Flame retardation 100% - 600% rated wattage load US UL-94 flame retardation test V-0 grade noncombustible
Remarks 1. Resistance and resistance tolerance were tested in-house with micro resistance meter.
2. Coating refers to UL-certified data provided by supplier.

Order Codes (FVR)

FVR 25W 2.5KR K
Part Number
Rated Power (W)
Resistance Value (Ω)
Indicates resistance value in units of ohms.
Resistance Tolerance (%)
K ±10%