Instruction Book
Page 32
Effective: March 2007
For more information visit:
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I.B
6513C80G
5-5 MISCELLANEOUS ITEMS
5-5.1 GROUND CONTACT
The ground contact is an assembly of spring loaded
fingers for all DHP-VR breaker designs providing a
means for disconnecting the grounding of the breaker
chassis, after it has been inserted into a switchgear cell
(Figure
5-16
).
The ground contact is located on the
underside of the chassis next to the secondary contact
block. 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 breaker is
pushed into the Test position. It remains engaged in all
positions from Test to and including Connected.
5-5.2 MOC AND TOC SWITCH OPERATIONS
A mechanism attached to the right side of the DHP-VR
breaker engages a channel member of the Mechanism
Operated Cell Switch (MOC) located in the switchgear
cell (Figures
5-14
and
5-15
).
This mechanism permits
the contacts of the MOC Switch to be correlated with the
breaker
’
s contact position.
NOTICE
All 15 kV. Type DHP-VR Breakers utilize the DHP-VR
SURE CLOSE MECHANISM to control MOC velocity
and closely mimic the dynamics and velocities of
older breakers. It is imperative that this mechanism
be adjusted to match the number of MOC switches
(from 0 to 3) mounted in the cell. Always make sure
the mechanism is properly adjusted in keeping with
paragraph 4-2 of this manual before any attempt is
made to insert the breaker into the cell.
In addition, the MOC pantograph must be checked in
keeping with the instructions outlines in paragraph
4-3 before any attempt is made to insert the breaker
into the cell.
The cell mounted Truck Operated Cell Switch (TOC) is
operated by movement of the breaker truck into or out of
the Connected position.
5-5.3 OPERATIONS COUNTER
All DHP-VR breakers are equipped with a mechanical
operations counter (Figures
3-2
and
3-4
)
.
As the breaker
opens, the linkage connected to the pole shaft lever
advances the counter reading by one.
5-6 LEVERING DEVICE
The purpose of the levering device is to move the breaker
between the Test and Connected positions. On the 7.5 or
15kV. DHP-VR, the levering-in mechanism is located in
the mechanism, while it is located in the breaker truck on
the 5kV. DHP-VR. The levering nut is fastened securely
to the guide tube and is loosely retained in a housing
fastened to the extreme rear of the breaker chassis
(Figures
5-17
and
5-18
)
.
The operation consists of engaging the rotatable levering
nut on the circuit breaker with the levering screw
mounted on the rear wall of the cell. By traversing the
levering nut along the levering screw, the breaker is
moved between positions within the switchgear housing.
The guide tube is slotted lengthwise for a distance about
equal to the travel distance of the breaker. The levering-in
shaft has two rectangular hardened keys welded to it
which slide in the guide tube slot. Thus, as the levering-in
shaft is rotated, the guide tube and nut also rotate.
As the breaker is levered in by clockwise rotation, the
keys on the levering-in shaft move toward the end of the
guide tube slot. As the rear key comes out of the slot,
the levering-in shaft turns freely and the breaker moves
no further.
F i g u r e 5 - 1 6 D H P - V R B r e a k e r G r o u n d C o n t a c t