Effective 11/97
I.B. 48006
Cutler-Hammer
Instructions for Mechanical-Latch Attachments for Type
SJA, SJD, SJO and SJS Contactors, 360 or 720 Amperes
DANGER
HAZARDOUS VOLTAGE.
READ AND UNDERSTAND THIS MANUAL AND THAT
PERTAINING TO ITS ELECTRICALLY-HELD
CONTACTOR (SEE TABLE I) IN THEIR ENTIRETY
BEFORE INSTALLING OR OPERATING THE CON-
TROLLER. INSTALLATION, ADJUSTMENT, REPAIR
AND MAINTENANCE OF THIS TYPE OF EQUIPMENT
MUST BE PERFORMED BY QUALIFIED PERSONNEL.
A QUALIFIED PERSON IS ONE WHO IS FAMILIAR
WITH THE CONSTRUCTION AND OPERATION OF
THIS EQUIPMENT AND THE HAZARDS INVOLVED.
APPLICATION
These instructions apply to Type SJA, SJD, SJO and SJS
contactors that are fitted with mechanical-latch attach-
ments.
Fig. 1 Type SJO with Latch Attachment
CAUTION
A LATCHED CONTACTOR SHOULD BE APPLIED
ONLY WHEN NECESSARY, AND WITH DUE RE-
GARD TO THE POSSIBLE FAILURE MODES OF
THE SYSTEM, FOR EXAMPLE, A POWER LOSS
OR SOLENOID COIL FAILURE. ONCE LATCHED,
THE CONTACTOR WILL REMAIN CLOSED, AL-
LOWING A FAILURE. SINCE POWER IS RE-
QUIRED TO TRIP THE UNLATCH SOLENOIDS,
PROVISION SHOULD BE MADE FOR MANUAL
TRIPPING, USING THE MECHANICAL TRIP ARM,
OR A STANDBY POWER SUPPLY, SHOULD THE
MAIN CONTROL POWER BE LOST.
OPERATION
When a Type SJ contactor with latch attachment is open,
the latch mechanism is unlatched and de-energized.
When the coil of a latch contactor is momentaily ener-
gized, its armature closes, closing the main power
TABLE I. REFERENCE MATERIAL
Electrically-Held Ampere Instruction
Contactor Type Rating I.L. or I.B.
Type SJA 360A I.B. 48002
Type SJA 720A I.B. 48005
Type SJD 360A I.B. 48004
Type SJO 360A I.L. 16-200-33
Type SJO 720A I.L. 17047
Type SJS 360A I.B. 48003
contacts. As the armature seals to the magnet, a spring
pushes the latch arm up into position behind the arma-
ture to hold it closed mechanically, at the same time an
auxiliary coil-clearing contact (L63) on the contactor
opens the contactor coil circuit to de-energize the
contactor magnet. Although the magnet is de-energized,
the contactor will remain latched closed until a trip coil is
energized or the latch is tripped mechanically by a push
against its trip arm.
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