Eaton Cutler-Hammer I.B. 48020 Instructions Manual

Effective 4/00I.B. 48020Cutler-HammerInstructions for Mechanical Latch Attachment for Type SL MediumVoltage Vacuum ContactorDANGERHAZARDOUS VOLTAGERead and understand this manual in its entirety beforeinstalling or operating a mechanical latch or contactor.Qualified personnel must perform installation, adjustment,and maintenance of this equipment. A qualified person isone who is familiar with the construction and operation ofthe equipment and who is aware of the hazards involved.This instruction book should not be considered all-inclu-sive regarding installation, adjustment, and maintenanceprocedures.Read and understand all instruction literature for the SLContactor before performing any work on the contactor orthe latch attachment.DESCRIPTIONThe SL Contactor in its standard configuration is a mag-netically held device. A mechanical latch attachment canbe added to the standard SL that will maintain thecontactor in the closed position when power is removedfrom the main operating coil. A separate unlatch coil mustthen be energized to allow the contactor to open.The unlatch coil is intermittently rated. Control powershould be applied to the coil only long enough to allow thecontactor to open. Two normally open auxiliary contacts(wired in parallel) on the contactor should be used to openthe circuit to the unlatch coil.Although the latch (closing) coil is continuously rated,power should be removed from the coil after the contactoris closed to insure that the contactor opens when theunlatch coil is energized. Make certain that the closepushbutton (or other device) is a momentary device thatwill apply power to the latch circuit for a short time only.Do not use a maintained device which will cause thecontactor to stay closed even after the unlatch coil isenergized. Do not wire a normally closed (NC) auxiliarycontact directly into the coil closing circuit to removepower from the coil. To do so may result in a failure tolatch since the contact may open before the coils havebeen powered sufficiently long enough to fully close thecontactor.A typical control schematic for a mechanically latchedcontactor is shown in Figure 2.Figure 1: SL Contactor with mechanical latch installed.Figure 2: Typical schematic for latched contactor

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