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Equipment Description
01.4IB.67000
In double breaker vertical sections, a steel duct
serves as a pull-box and barrier to separate the
two outgoing cable circuits.
The primary termination space of a unit is
accessible by removal of the bolted rear cover.
N. VOLTAGE TRANSFORMERS
The voltage transformers are mounted on a
rollout carriage equipped with primary and
secondary disconnecting devices. When the
voltage transformers are disconnected, they
are at a safe striking distance from all live parts
of the metal-clad switchgear. In addition, a
grounding device is provided which contacts
the fuses when the voltage transformers are
disconnected, effectively discharging the
transformers. In this position, the transformer
fuses may be safely removed and replaced.
When the voltage transformer rollout tray is
in the disconnected position, the rear barrier
of the tray effectively deters access to the
stationary primary disconnects mounted in the
compartment behind the rollout tray. However,
these stationary primary disconnects may
remain energized.
O. CURRENT-LIMITING FUSES AND CONTROL POWER
TRANSFORMER
Current limiting fuses with high interrupting
rating are sometimes used in metal-clad
switchgear to protect small transformers
or circuits where circuit breakers cannot be
economically or functionally justified.
The fuses are mounted on a moveable carriage
equipped with primary and secondary
disconnecting devices. Single phase control
power transformers of 15kV and smaller and
their secondary breaker are mounted on the
carriage with the fuses. Larger control power
transformers, up to 37.5kV single-phase or
75kV three-phase , are located in the cable
compartment behind their associated fuse
carriage and their secondary breaker is located
behind a hinged cover on the upper cable
compartment.
Do not remove the rollout tray from its rails
without first deenergizing the primary circuit
to which the roll-out connects. Removing the
tray makes the stationary primary disconnect
devices accessible.
!
When fuses are disconnected, they are at a
safe striking distance from all live parts of the
switchgear. In addition, a grounding device is
provided which contacts the fuses after they
are disconnected, effectively removing any
static charge from the fuses. In this position,
the fuses may be safely removed and replaced.
The primary disconnecting devices are capable
of interrupting transformer magnetizing
current, but should not be used to interrupt
load current. Mechanical or key interlocks are
applied to prevent operating the disconnecting
device while the load is connected. This is
generally accomplished by interlocking so
that the transformer secondary breaker must
be locked in the open position before the
disconnecting device can be connected or
disconnected.
Current-limiting fuse and control power
transformer rollouts are located in auxiliary
units.
P. DUMMY REMOVABLE ELEMENT (TYPE PVD)
Dummy removable elements are used as a
means of isolating circuits or bus sections
where operation is infrequent and a circuit
breaker cannot be economically justified. The
device consists of a circuit breaker mechanism
frame and primary insulator supports with
six primary studs including disconnecting
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