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Contact ResistanceContact / relay resistance(voltage drop)Electrical resistance between the relay load terminals while the respective contact is closed. The resistance can be obtained out of the ratio of the voltage drop across the relay and the load current (Ohm´s law). Due to slight contact corrosion, the contact voltage drop can be higher (up to 250 mV) for small load currents. For loads in the Ampere range, the current locally generates heat evaporating the cover layer (fritting) and reducing the resistance. Note: Alternatively, the voltage drop at a particular current intensity is specified. Measuring voltage Maximum voltage (no-load voltage) that lies across the opened contact when the contact resistance is measured. Contact voltage drop Drop in voltage at the closed contact at a predetermined contact current. Recommended for loads greater than... The specified contact resistance is reached reliably only above a particular load. Considerably increased contact resistances can occur with smaller loads. |