The under-speed switching PL60 P 60-23 is a low-cost, reliable, simple and universal monitoring device for shaft speed and other rotating devices. The under-speed switch is placed in a weatherproof, sealed, corrosion resistant housing, allowing exposure to work in harsh environments. Non-contact proximity detector with long life and low maintenance cost. Two bolts are fixed to ensure easy installation. Integrated structure, centralized control device, simple setting or troubleshooting, no moving parts, no wear, long safety life. Start delay :10 seconds delay alarm when the working speed has not been reached during the start of the rotating equipment. Technical parameters: Voltage :110/220 VAC±15% frequency :47-62 Hz; Alarm contacts: two (NO/NC optional); Operating range :60-600 pulses/min; From sensor to iron element furthest :10 mm; Shell: high quality nylon weatherproof, anti-corrosion, working temperature range :-20℃~65℃; Alarm contact :2 A,350Vac, no inductive load; release point :15~100% of the scope of work. the optional pl60 type under-speed switch adds an output signal of 4-20 ma corresponding to the corresponding speed.