Interlocks And Interfacing; Levering Mechanism; Operations Counter; Ground Contact - Eaton 50VCPW-ND250 Installation, Operation And Maintenance Manual

I.B. 32-255-1G

5-5 INTERLOCKS AND INTERFACING

Refer to Paragraph 4-9 of this manual for detailed infor-
mation concerning circuit breaker interlocks and their
interfacing with a switchgear structure compartment. In
addition, refer to the instruction manual supplied with
the switchgear assembly.

5-6 LEVERING MECHANISM

The purpose of the levering device is to move the circuit
breaker between the TEST and CONNECTED posi-
tions. For Type VCP-W circuit breakers, the device is a
drive screw and drive nut. Although the device is
mounted in the switchgear compartment, a brief
description here will help understand the operation
(Figures 4-2 and 4-4). For additional information on the
insertion and removal of a circuit breaker from its com-
partment refer to paragraph 4-8.1 in this manual.
The levering device consists of a drive screw, a drive
nut, two side rails and a sliding cage. In the TEST posi-
tion, the nut is all the way to the front. As the circuit
breaker is pushed in, the levering latch snaps on the
nut. Turning the crank clockwise while pushing forward
advances the circuit breaker toward the CONNECTED
position. During this travel, the floor tripper TRIP roller
is lifted up holding the circuit breaker trip free. When the
circuit breaker reaches the CONNECTED position, the
crank cannot be turned any further. A red flag indicates
that the circuit breaker is fully engaged.
If the circuit breaker is closed in the CONNECTED posi-
tion, the slider cannot be pushed forward to permit
engagement of the levering crank. After tripping the cir-
cuit breaker, the levering crank can be engaged and the
circuit breaker withdrawn to the TEST position by turn-
ing the levering crank counterclockwise. This position is
indicated by no further motion of the crank.
The circuit breaker levering latch can be disengaged
only when the circuit breaker is in the TEST position by
lifting the latch release. As the circuit breaker is with-
drawn, it comes out with the contacts open and the
springs discharged because of the floor tripping and
spring release interlocks.
Effective 12/02

5-7 OPERATIONS COUNTER

All circuit breakers are equipped with a mechanical
operations counter. As the circuit breaker opens, the
linkage connected to the pole shaft lever advances the
counter reading by one (Figure 3-3).

5-8 GROUND CONTACT

The ground contact is an assembly of spring loaded fin-
gers providing a disconnectable means for grounding
the circuit breaker chassis, after it has been inserted
into a switchgear structure. The ground contact is locat-
ed on the left side of the circuit breaker under the
mechanism bottom pan. An extension of the switchgear
ground bus is secured to the cell floor in such a position
to engage the ground contact automatically, when the
circuit breaker is moved into the TEST position. It
remains engaged in all other circuit breaker positions
within the cell (Figures 4-2 and 4-4).

5-9 MOC AND TOC SWITCH OPERATIONS

The MOC (mechanism operated control) switch opera-
tor is coupled to the pole shaft (Figure 4-4). In the TEST
and CONNECTED positions of the circuit breaker, the
operator aligns directly above the MOC switch bell
crank levers in the compartment. As the circuit breaker
closes, the operator moves down and pushes the bell
crank lever to change the MOC switch contact position.
Thus, the MOC switch contacts operate in the same
manner as the auxiliary switch contacts in the circuit
breaker. Although the MOC switch operator is provided
on all circuit breakers, the compartment mounted MOC
switches are only provided when specified with the
switchgear order.
The TOC (truck operated control) switch operator is
mounted inside the right foot of the circuit breaker
(Figure 4-4). It operates the TOC switch as the circuit
breaker moves to the CONNECTED position in the
switchgear compartment.
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