What is the voltage tolerance level at nominal voltage for the electrical auxiliaries used in Low Voltage Circuit Breakers


01 March 2021

The voltage tolerance level for the electrical auxiliaries (example: undervoltage release(Mn), shunt coil(Mx)) used in Low Voltage Circuit Breakers is defined as per the IEC 60947-2 standard.
The tolerance level defined by IEC60947-2 is 0.85% for minimum nominal voltage (Un) and 1.1% for maximum nominal voltage (Un).
For Un = 230/240V, Minimum tolerance Level is (0.85% of 230V AC) = 195.5V, Maximum tolerance Level is (1.1% of 240V AC) = 264 VAC. This means voltage range : 195.5 VAC - 264 VAC.