Stored Energy Mechanism; Electrical Position; Trip-Free Operation; Anti-Pump Feature - Eaton 50DH-VE-50AXU-1200A Instruction Book

at the ends of the conductors provide means for connecting
and disconnecting the circuit breaker to the bus terminals in the
switchgear compartment.

4.5 STORED ENERGY MECHANISM

The spring-type stored energy operating mechanism is mounted
on the circuit breaker frame and in the front of the circuit breaker.
Manual closing and opening controls are at the front panel (Figure
Set 3.3). They are accessible while the circuit breaker is in any of its
four basic positions. (See Section 5 in this manual)
The mechanism stores the closing energy by charging the closing
springs. When released, the stored energy closes the circuit breaker,
charges the wipe and resets the opening springs. The mechanism
may rest in any one of the four positions shown in Figure 4.9 as
follows:
a. Circuit breaker open, closing springs discharged.
b. Circuit breaker open, closing springs charged.
c. Circuit breaker closed, closing springs discharged.
d. Circuit breaker closed, closing springs charged.
The mechanism is a mechanically "trip-free" design. Trip-free is
defined later in this section.
In normal operation the closing spring is charged by the spring
charging motor, and the circuit breaker is closed electrically by the
switchgear control circuit signal to energize the spring release coil.
Tripping is caused by energizing the trip coil through the control
circuit.
For maintenance inspection purposes the closing springs can be
charged manually by using the handle located at the front of the
mechanism and the circuit breaker can be closed and tripped by
pushing the "ON" and "OFF" buttons on the front panel.
 DANGER
KEEP HANDS AND FINGERS AWAY FROM CIRCUIT BREAKER'S INTERNAL
PARTS WHILE THE CIRCUIT BREAKER CONTACTS ARE CLOSED OR THE
CLOSING SPRINGS ARE CHARGED. THE CIRCUIT BREAKER CONTACTS
MAY OPEN OR THE CLOSING SPRINGS DISCHARGE CAUSING CRUSHING
INJURY. DISCHARGE THE SPRINGS AND OPEN THE CIRCUIT BREAKER
BEFORE PERFORMING ANY MAINTENANCE, INSPECTION OR REPAIR ON
THE CIRCUIT BREAKER.
THE DESIGN OF THIS CIRCUIT BREAKER ALLOWS MECHANICAL CLOSING
AND TRIPPING OF THE CIRCUIT BREAKER WHILE IT IS IN THE "CONNECT"
POSITION. HOWEVER, THE CIRCUIT BREAKER SHOULD BE CLOSED
MECHANICALLY ONLY IF THERE IS POSITIVE VERIFICATION THAT LOAD
SIDE CONDITIONS PERMIT. IT IS RECOMMENDED THAT CLOSING THE
CIRCUIT BREAKER IN THE "CONNECT" POSITION ALWAYS BE DONE WITH
THE CUBICLE DOOR CLOSED. FAILURE TO FOLLOW THESE DIRECTIONS
MAY CAUSE DEATH, PERSONAL INJURY, OR PROPERTY DAMAGE.
ELECTRICAL TRIPPING CAN BE VERIFIED WHEN THE CIRCUIT BREAKER IS
IN THE "TEST" POSITION.

4.6 ELECTRICAL POSITION

For electrically operated circuit breakers, the springs are normally
charged through the use of a rugged electrical motor operator. The
springs can, however, be manually charged. To manually charge the
springs, insert one finger in the recess behind the charging handle
and pull out. This permits a hand to grasp the handle and begin
charging. It takes a number of downward strokes on the charging
handle to complete the manual charging process. Keep in mind that
it is possible to manually recharge the springs immediately after
closing the circuit breaker and before it has been tripped open.
Electrically operated circuit breakers can also be manually closed
and opened through the use of the front mounted manual "ON" and
manual "OFF" push-buttons. A factory supplied electrically operated
circuit breaker is equipped as standard with a spring release to close
50DH-VR-50AXU / 50XU / 75U / 75ARU - 600 / 1200A
the circuit breaker electrically and a shunt trip to trip (open) the
circuit breaker electrically. A second shunt trip or an undervoltage
release are available optional devices.
The electrical motor operator can be installed in the field. Manually
operated circuit breakers are pre-wired to readily accept this change.

4.7 TRIP-FREE OPERATION

When the manual trip button is held pressed, any attempt to close
the circuit breaker will be prevented.

4.8 ANTI-PUMP FEATURE

The VCP-TR circuit breaker has a standard mechanical anti-pump
feature. If the circuit breaker is open, it only accepts one attempt to
reclose when the close command continues uninterrupted.

4.9 LATCH CHECK SWITCH

Any VCP-TR circuit breaker capable of being electrically closed is
provided with a latch check switch. The latch check switch ensures
that all closing conditions are met before the circuit breaker can be
electrically closed.

4.10 TIMING

The opening and closing times for the circuit breakers vary
depending upon the control voltage and the power rating. Typical
values for VCP-TR circuit breakers are given below:
Closing Time (from initiation of close signal to contact close)
- 60 milliseconds
Opening Time (from initiation of trip signal to contact break)
- 60 to 73 milliseconds
Reclosing Time (from initiation to trip signal to contact close)
- 250 milliseconds

4.11 SECONDARY DISCONNECT BLOCK

The circuit breaker control circuit is connected to the switchgear
control through an 18-point secondary disconnect block (Figure
Set 3.3). The movable slide arrangement is provided to allow for
block extension during operational checks with the circuit breaker
in the "TEST" position. The contacts engage automatically when
the circuit breaker is racked into the "CONNECT" position, or it can
be engaged while the circuit breaker is in the "TEST" position by
releasing the latch pin and pushing forward on the slider located at
the lower left hand of the circuit breaker frame. The socket half of
the connection is located in the switchgear and a jumper of multi-
conductor cable, included with the switchgear, can complete with
control connections (for testing) when the circuit breaker is in the
"WITHDRAWN" position as described in Section 3. The latch pin
causes the secondary disconnect block to disengage whenever the
circuit breaker is racked out of the "CONNECT" position.

4.12 INTERLOCKS

INTERLOCKS ARE PROTECTIVE DEVICES FOR PERSONNEL AND
EQUIPMENT. DO NOT BYPASS, MODIFY, OR MAKE INOPERATIVE ANY
INTERLOCKS. DOING SO COULD CAUSE DEATH, SERIOUS PERSONAL
INJURY, AND/OR PROPERTY DAMAGE.
There are several interlocks built into the VR-Series vacuum
replacement circuit breakers. Each of these interlocks, though
different in form, duplicate or exceed in function that of the original
circuit breaker. These interlocks exist to safeguard personnel and
equipment. The basic premise behind the interlocking arrangement
on the vacuum replacement circuit breaker is that the circuit breaker
must not be inserted into or removed from a live circuit while the
main contacts are closed. Also considered in the interlocking is that
the circuit breaker should pose no greater risk than necessary to the
operator in or out of the cell. In addition to the original interlocks,
VR-Series circuit breakers provide an anti-close interlock.
Instruction Book IB182012EN March 2017 www.eaton.com
Replacement Circuit Breaker
 DANGER
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