The MPK-257 digital very low resistance ohmmeter is a portable, microprocessor-controlled instrument used to accurately measure resistances of switches and circuit breaker contacts, transformer and motor windings, wire and cable samples, joints in busbars, etc., using test currents from 1mA up to 10 A.
 

It uses the Kelvin-type, four-terminals measurement principle, thus eliminating errors caused by lead and contact resistances.
 

Resistance readings are shown in the alphanumeric display with up to a 4½ digit-resolution. It allows to measure resistances of up to 2,000 Ω, with a resolution down to 0.1 µΩ.
 

Measurements accuracy is guaranteed by the state-of-the-art system for signal amplification, offset-free and with long-term stability.The equipment has a USB interface that allows to download the measured values to a computer for their later analysis.
 

The open circuit output voltage is of up to 10 V, depending on the selected test current, reducing the stabilization time for the test current when highly inductive elements are measured.
 

The measurement circuit has an effective protection against voltage peaks originated by those inductances.
 

Operation is very simple: Just connect the leads, switch-on the equipment, select the test current and press the start button. After a few seconds (depending on inductance of the element), direct reading appears on the display with the measure unit indication (Ω, mΩ or µΩ). If it is necessary, the display will show messages to help the operator (Low battery, Over range, etc).
 

The equipment is housed in a rugged plastic case with a hinged lid and carrying handle. It is a portable, strong, impact resistant and lightweight equipment, suitable to be used in field, under severe weather conditions. It supplies very reliable and accurate measurements both in laboratory and out in the field.