Extech prt200 phase rotation tester extech prt200 the extech prt200 phase rotation tester is a non contact phase sequence tester which checks phase sequence and phase status it works with up to 1000v ac with led and audible indication the leds indicate phase orientation clockwise or counter clockwise and whether each phase is live its beeper sounds intermittently when correct phases are detected and continuously if the phase squence is reversed the meter has a durable housing with back