Instruction Book
Page 20
Effective: March 2007
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I.B
6513C80G
SECTION 5: DESCRIPTION AND
O P E R AT I O N
Cutler-Hammer Type DHP-VR breakers are horizontal
drawout vacuum type removable interrupting elements
for use in existing DHP Metal-Clad Switchgear. The
breakers use vacuum interrupters to close and open the
primary circuit. The mechanism is a front mounted
spring stored energy type, which not only aids with
personnel safety, but also provides ease of inspection
and accessibility for servicing. The same basic
mechanism is used for all ratings.
The DHP-VR vacuum circuit breaker is a direct roll in
replacement for DHP air magnetic and DVP vacuum
circuit breakers. It is wheel mounted for ease of
handling and installation, and rolls in and out of the
existing cell on the floor. Modifications to the existing
DHP or DVP structures are not necessary in order to
use DHP-VR breakers.
DHP-VR vacuum circuit breakers correctly interface with
compartment cell switches (MOC and TOC switches).
Circuit breaker coding plates are maintained to prevent
an underrated circuit breaker from being installed in the
switchgear.
Safety interlocks, inherent in the original switchgear
design and required by ANSI Standards, are also
maintained.
Figure 5-1 DHP-VR 5k V Interrupter Assembly
The primary insulation used on 5kV. DHP-VR vacuum
circuit breakers is glass polyester, while the primary
insulation used on 7.5 and 15 kV. DHP-VR vacuum
circuit breakers is cycloaliphatic epoxy. Type SIS
AW G# 14 wire, with cross-linked polyolefin insulation is
used on all DHP-VR control circuits. Secondary control
terminations on all DHP-VR breakers are ring type
terminations, consistent with existing DHP circuit
breakers.
5-1 INTERRUPTER ASSEMBLY
Vacuum interrupters are mounted vertically and are sup-
ported from the fixed stem clamped to the bottom
conductor on the 5kV. design (Figure
5-1
)
,
and the top
conductor on the 7.5 or 15kV. design (Figure
5-2
)
.
A
close inspection of the two figures will reveal that the
5kV. design is actually inverted, relative to the 7.5 or
15kV. design. In both instances, however, the DHP-VR
includes the Cutler-Hammer patented V-flex current
transfer system. The current transfer system itself
consists of a series of tin-plated, high-conductivity copper
leaf conductors that are swaged onto the movable
interrupter stem. This provides a multipoint contact
resulting in low electrical and thermal resistance. Since
the cur-rent transfer from the movable stem to the circuit
breaker main conductor is a nonsliding design, no
maintenance is required.
Figure 5-2 DHP-VR 7.5 or 15 kV Interrupter Assembly
