1. Pick the Right Relay or Module
The best way to avoid creating high resistance contacts is to read the relay module specifications carefully. Most relays (all armature relays) should have minimum voltage and current specifications. Make sure that your application will be above these values.
Use reed relays if possible for low current and voltage applications. Because of the inert atmosphere surrounding the contacts, they typically don’t have this type of increased contact resistance behavior.
2. Use a Different Type of Measurement Device
To increase the current used when making 2-wire resistance measurements a precision power supply like the PXI-4110 can be used. It is possible to source a higher current (e.g. 10mA) and then read the power supply output voltage. Combining these two values will yield the resistance. This method will help ensure that the minimum voltage or current is met or exceeded. In the event of high contact resistance the current can be increased until the relay contacts are clean again. This current should not exceed 100mA.
3. Use 4-Wire Resistance Measurement
Performing 4-wire resistance measurements eliminate the effects of contact resistance. This is the preferred method for doing low resistance measurements.