Only the highest quality components, all UL listed or UL recognized, are used throughout to assure the best possible reliability. The cabinet is fabricated of heavy gauge reinforced steel with drip-proof hood. All field wiring and service connections may be made from the front, allowing the controller to be mounted flush against a wall.
The controller is completely wired, assembled, and tested at the factory before shipment, and ready for immediate installation.
Wye-Delta motors have all six leads brought out to the motor terminal box. These leads are connected by the contoller first in the Wye configuration which draws only 33% of normal starting current and develops 33% of normal starting torque. After a short time delay, the controller then connects the motor winding in a Delta configuration, applying full voltage and drawing full load running current and developing full running torque.
The MP435 closed transition types provide a smooth transition from Wye to Delta by keeping the motor continuously energized during the transition period. This is accomplished by means of resistors which are connected in the circuit during the momentary period of transition from Wye to Delta.
Metron Wye-Delta Controllers incorporate a mechanical as well as electrical interlock to prevent the Wye connecting contactor from being energized at the same time as the Delta contactor.
An emergency start lever to close starting contactor independent of automatic control circuits. When used, this lever will bypass the reduced current start feature and start the motor with full inrush current drawn from the power source
After a minimum run period and all starting causes have returned to normal, the solid state controller will initiate a stop sequence. This furncion will reduce surges in the pumping system during stopping a centrifugal pump by smoothly decelerating the motor at a selectable rate.