Eaton Cutler-Hammer SJA User manual

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 UNDERSTANDTHIS 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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Page 2
Effective 11/97
OPERATION (Continued)
The latch may have one or two trip (unlatch) solenoids.
Each solenoid has an isolated trip coil that may be AC or
DC operated. Either or both solenoids, when energized,
will trip the latch arm by pushing down the latch arm
located below the contactor armature, thus allowing the
armature to move into the open-contacts position. The
latch arm has a roller-bearing cam wheel on the end that
engages the armature, so that friction is minimized and
the trip action is fast.
The contactor pickup coil and trip solenoid coils are rated for
intermittent duty and will burn-out if energized continuously
under normal operating conditions. The contactor coil may
be operated at its rated voltage continuously if the armature
has been sealed against the magnet and both windings of
the coil are connected in series. There are many possible
operating schemes and diagrams, and the installer must
check the operation of the latch against the specified
diagram for the specific application. It is recommended that
the contactor and solenoid coils be automatically de-
energized by auxiliary contacts on the contactor itself,
without depending on supplementary relays elsewhere.
The latch sensitivity is adjustable. If unlatching occurs
accidentally from vibration or impact, the sensitivity
should be decreased. If either unlatch solenoid fails to
trip the latch when rated solenoid voltage is applied, then
the sensitivity should be increased. Refer to the section
on MAINTENANCE.
CONTROL POWER REQUIREMENTS
A control power transformer, whose primary winding is
connected to the same source supplying power to the
motor, is the usual source of control power used to close
the contactor. This same transformer can also be used
as the voltage source for the trip (unlatch-open) sole-
noids, but a manual operator (pushbutton type) must be
installed in order to open the contactor in case of a power
failure. Where a standby control voltage source (usually
battery-supplied DC) is available to operate a trip sole-
noid, the manual operation is not required. Most solenoid
coils furnished have both an AC and a DC intermittent
duty rating. See Table II for inrush VA requirements.
Some latch attachments are supplied with two trip
solenoids, each rated for a different voltage. The latch
attachment will unlatch when either solenoid is energized.
MANUAL UNLATCH OPERATOR
Where it is desirable or necessary to add a manual unlatch
(trip) operator, use Part Number 10935H3, an external
operator kit marked RESET. This operator requires a
1.20" (30 mm) diameter hole opposite the trip arm of the
latch attachment. The location of the latch trip target
center (1.20" diameter hole) is shown in Figure 2. A
faster and probably more accurate way to locate the
target center is to use a temporary clamp to attach a 3-
inch (76 mm) right angle bracket to the face of the trip
arm with one leg of the bracket pointing towards the
door. Attach to this leg an eraser-tipped pencil or a strip
of any sponge material that will absorb stamp pad ink or
similar marking material.
Position the pencil along the extended leg so that the ink-
soaked projection will strike the inside of the door when it
is closed. Use the mark on the door to select the unlatch
(reset) operator center.
After installing the RESET operator, adjust its operating
length (cutting the threaded stud if necessary) so that the
trip arm can be pushed sufficiently far to unlatch the
contactor. Verify that door deflection does not unlatch the
contactor accidentally.
INSTALLATION
This industrial type control is designed to be installed,
operated, and maintained by adequately trained person-
nel, with adequate supervision. These instructions do not
cover all details, variations, or combinations of the
equipment, its storage, delivery, installation, check-out,
safe operation, or maintenance. Care must be exercised
to comply with local, state, and national regulations, as
well as safety practices, for this class of equipment.
TABLE II. COIL INRUSH DATA
Coil Function Rating Volt-Amperes
Close Contactor 110-120VAC 1300
Close Contactor 220-240VAC 1400
Close Contactor 125 VDC 1500
Close Contactor 250 VDC 1600
Open Contactor AC 225
Open Contactor 24 VDC 600
Open Contactor 48 VDC 190
Open Contactor 125 VDC 300
Open Contactor 230 VDC 265
DANGER
WARNING: ALL WORK ONTHIS CONTACTOR SHOULD
BE DONEWITHTHE MAIN DISCONNECT DEVICE OPEN.
ASWITH ANY CONTACTOR OFTHISVOLTAGE CLASS,
THERE IS DANGER OF ELECTROCUTION AND/OR
SEVERE BURNS. MAKE CERTAINTHAT POWER IS OFF.

I.B. 48006 Page 3
Effective 11/97
Fig. 2 Trip Target Location (Dimensions In Inches)
CONTACTOR
CENTERLINE
AMPGARDDOOR
TRIPTARGET FOR LATCH
.30TRAVEL
REQ’D.TO
TRIP
(7.62 mm)
4.30
(109.2 mm)
14.2
(360.7 mm)
10.20
(259.1 mm)
8.00
(203.2 mm)
2.75
(69.9 mm)
9.00
(228.6 mm)
LATCH TRIP
TARGET
8.07
(205.0 mm)
8.50
(215.9 mm)
2.75
(69.9 mm)
4.06
(103.1 mm)
.30TRAVEL
REQ’D.TO
TRIP
(7.62 mm)
AMPGARDDOOR
5259C59 TYPES SJO, SJD AND SJS
TYPE SJA

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Page 4
Effective 11/97
OPERATION
Figure 3 shows a latch assembly before it is mounted on
a contactor. The enlarged detail shown in Figure 4 shows
the relationship between the cam roller on the end of the
latch arm and a notch in the lower left corner of the
contactor armature. When the latch is installed, it
appears as shown in the lower portion of Figure 4.
Latch sensitivity can be understood by studying the inset
of Figure 4, which is a magnified detail view showing the
lower left corner of the armature and the cam roller. The
cam roller travels between positions (U) and (L) through
an arc around the latch shaft. In the unlatched (open)
contactor position, the cam roller is in position (U). It
cannot travel upward to position (L) even though the latch
spring is pushing the latch arm upward because latch
edge (F) of the armature stops it. However, when the
contactor operating coil is energized, the armature
rotates toward the magnet and latch edge (F) travels
across the cam roller easily. As latch edge (E) passes
the centerline of the cam roller, the roller starts moving
upward, driven by the latch spring. By the time the
armature reaches the magnet, the cam roller passes
completely by latch edge (E) into position (L), and the
contactor is latched closed.
The cam roller cannot travel to the top of the notch in the
armature because the latch arm stops against the latch
adjustment bolt. The further into the notch the cam roller
penetrates, the less sensitive the latch becomes.
There will always be some “free-play”clearance between
the contactor armature and magnet in order to provide
free motion. This clearance needs to be only a few
thousandths of an inch; so for practical purposes, the
contactor is held “fully” closed.
When either or both trip solenoids are momentarily
energized, their armatures push the latch arm downward
against its spring. As the centerline of the cam roller
passes below latch edge (E) of the armature, the
contactor armature will snap to the fully open position;
i.e., the contacts are open.
Fig. 3 Mechanical Latch Assembly
5259C56

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Effective 11/97
If the latch has been de-energized with an adjustment
that allows the cam roller to travel high into the armature
notch when latched, the trip solenoids have an increased
resistance of their push. In a poorly adjusted latch, this
may prevent tripping at 80% of trip solenoid voltage, in
which case the latch must be made more sensitive.
CHECK-OUT, MECHANICAL
Refer to the instruction material relating to the electri-
cally-held version of the contactor. See Table I.
Make sure all power circuits are isolated. The contactor
can be checked in its enclosure or outside. If the starter
is a new factory assembly it is probably easiest to test
the contactor as installed. Check all mechanical inter-
locks as installed, to make certain that they function
properly.
Fig. 4 Mechanical Latch Installed, 360A Contactor
CAUTION
A LATCH IS SOMEWHAT LIKE A MOUSETRAP. USE
CARE TO PROTECT FINGERS INTHE EVENT OF AN
ACCIDENTAL TRIP DURING CHECK-OUT.
5259C57