Carlo Gavazzi has launched the DUA55 a single phase relay for detection of incorrect mains voltage; designed to meet the specific requirements set out in the IET Wiring Regulations, BS7671:2018 to ensure that all new EV charge points are electrically safe.
The relay operates when the monitored voltage is within the voltage window 207V to 253V AC in order to protect against over and under voltage; its alarm output has also been fixed at 4 seconds to comply with the regulations. Stopping any incorrect power supply voltage from the desired one.
Only 17.5 mm wide and is suitable for both rear and front panel mounting on a single phase EV charging unit or a separate box, this will ensure the user is protected against electric shock if the PEN were to become damaged.
The relay sends an output signal to the EV charger to tell it to electrically disconnect the vehicle from the live conductors of the supply and from protective earth within 5 seconds (in accordance with Regulation 5220.127.116.11(ii)), in the event of the utilisation voltage at the charging point, between the line and neutral conductors, being greater than 253 V rms or less than 207 V rms.
For additional safety, the relay can only be reset if the voltage between line and neutral conductors is in the range 207 to 253 V rms.