This product is part of the Nema Pressure Switches range, an offer of mechanical alternators. This mechanical alternator has 4 normally closed, snap action, DPST-DB (double pole single throw, double break) form YY contacts. 9039 mechanical alternating switches are UL Listed and CSA certified. The closed tank mechanical alternator supports screw-in bush mounting method and 90 (offset) float rod angle for operating in left position. It is furnished with screw clamp terminals for electrical connection and 8 knockouts for 1/2inch or 3/4inch conduit. Offers electrical durability of 100 cycles and mechanical durability of 300 cycles. The enclosure is made of painted cold-rolled steel. It weighs 8.67lb. It is suitable for pressure controlling or monitoring of water pumps, compressors, agricultural/irrigation water systems, moulding presses, injection moulders, grinding machines, machining centres, complex and special machines. It is a NEMA 1 rated product. This product is certified by CE, CSA and UL. Meets UL 508 standards. When liquid level rises to the first level, one pump turns on. Both pumps automatically turn on when a peak condition occurs and the liquid level continues to rise. If form N5 or N25 is present and the water level continues to rise. Mechanical alternator provides a simple, positive means of mechanically alternating two pumps or motors. This alternator is used on devices that are installed in a duplex system with a common tank.