Kelvin Bridge


This instrument employs the double Kelvin Bridge principle for accurate measurement of low resistances. Twin, 5-position ratio arm, combined with a decade & slide wire, provide a wide range of resistance measurement, i.e. 0.2 micro-ohms to 11 ohms with high accuracy. Two or four terminal measurements may be employed. Current up to 10 A can be used during measurement.

All controls are simple to operate. Thermal e.m.f. may be taken into account using the three position (Normal/ Off/ Reverse) current switch. Both ratio arms are operated by one switch. The press keys give full and reduced sensitivity control for the galvanometer detector. Readings are obtained direct from decade and slide wire scale multiplied by ratio arm switch setting. All dials, keys & terminals are positioned on a instrument panel mounted in polished wooden case with hinged lid.

For measurement of resistance of thicker wires, strips and rods up to 15 mm dia, Conductor Clamps are also available. These Conductor Clamps have terminals for current as well as potential connections and are available for lengths of 100 cm and 50 cm.

  • Especially suited for measuring low resistances
  • Two or four terminal measurements can be performed
  • Lead Balancing not necessary when lead resistances lie within specified limits

Ratio Arm Setting

Decade Resistance x ratio arm Setting

Slide wire resistance x ratio arm Setting


10 Steps of 0.1 milli ohm

500 div. of 0.2 micro-ohm


10 Steps of 1 milli ohm

500 div. of 2 micro-ohms


10 Steps of 10 milli ohms

500 div. of 20 micro-ohms


10 Steps of 100 milli ohms

500 div. of 200 micro-ohms


10 Steps of 1 ohm

500 div. of 2 milli -ohms

Accuracy: ± 0.05 % or ± 1 slide wire scale division whichever is greater.

Size & Weight: 430 mm x 280 mm x 165 mm
8.2 Kg. (approx.)

Conductor Clamp, PL39.01-suitable for wire/ rod length 100 cm.

Conductor Clamp, PL39.02-suitable for wire/ rod length 50 cm.

For convenience of operation, a mains operated 10 A DC power supply Cat no.:PL39PS, power: 230V AC, 50 Hz is also available

Recommended Accessories:

  • Light spot Galvanometer, Cat No. PL64
  • Conductor Clamp, Cat.No. PL39.01 or Cat. No. PL39.02
  • DC Power supply, 10Amp., Cat.No.: PS 39PS
  • DC Power Supply, 5 Amp, Cat.No. PL39PS/1

Measurements of low resistance, conductivity and calibration of other instruments.

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