Gic mg21dh 3 phase 3 wire phase failure rotation assymmetry spco gic mg21dh p the mg21dh voltage relay will monitor your incoming 3 phase supply although it is compact in size just 17 5mm it is fully featured with over and under voltage adjustment and delay timers the relay is suitable for world wide export markets p gic mg21dh 3 phase 3 wire phase failure rotation assymmetry spco