Powell PowlVac ARG 4 Series, Instruction Bulletin

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7

Equipment Description

01.4IB.50023A

Ch 3  Equipment Description

A.  G

enerAl

The PowlVac® Electrically Operated Ground and 

Test Devices stated in 

Ch 1 General Information, 

A. Scope

 are drawout elements that can be 

inserted into the circuit breaker compartment 

in the same manner as a PowlVac circuit 

breaker.

The ground and test device provides a 

means for obtaining access to the primary 

disconnecting devices of the switchgear 

compartment for purposes of grounding the 

primary circuits or conducting certain high 

voltage test procedures such as conducting 

high voltage withstand (hipot) tests.

The grounding switch is operated by a stored 

energy mechanism.  It is capable of applying 

the ground against a live circuit if operational 

errors have not cleared the circuit.  However, in 

such a case, the relaying at the source of power 

is expected to cause the source interrupter to 

clear the circuit.

B.  r

AtInG

The ground and test device has ratings similar 

to a power circuit breaker, with two very 

important exceptions:  it has no continuous 

current rating, and it has no interrupting 

rating.  This device has no continuous current 

rating because it cannot be used to carry a 

continuous current.  It has no interrupting 

rating (or any of the ratings associated with the 

interrupting rating, such as interrupting time, 

etc.) because it is not designed to interrupt 

current.

In general, the ratings applied to any ground 

and test device are the same as those applied 

to the power circuit breaker it is designed to 

temporarily replace for grounding and testing 

purposes.  The rating nameplate 

(Figure 1, i)

on the front of the device will give the ratings 

applicable to any individual device.

c.  p

rImAry

 d

ISconnect

 S

tABS

The ground and test device has three (3) 

primary disconnect stabs 

(Figure 2, f)

 similar in 

design to those on the PowlVac circuit breaker.  

These three disconnects will connect the three 

stationary primary disconnect stabs in the 

switchgear compartment when the ground 

and test device is racked into the connected 

position.  They are mounted on the rear of a 

heavy insulated barrier near the rear of the 

ground and test device.

d.  G

round

 m

AkInG

 S

WItch

A three-pole, single-throw ground making 

switch is mounted on the front of the insulating 

barrier on which the selector switch hinges are 

mounted.  The three stationary contacts of the 

grounding switch 

(Figure 3, a)

 are connected to 

the three primary disconnect stabs so that the 

ground making switch can be connected to the 

upper set of primary disconnect stabs, allowing 

the line side of the switchgear compartment to 

be grounded.

The moving contacts and blades of the ground 

making switch 

(Figure 3, b)

 are operated by a 

high-speed stored energy mechanism.  The 

ground making switch contact structure is 

specially designed for the close-and-latch 

and short-time current carrying duties to 

which it can be subjected.  These contacts 

are not designed for continuous current 

carrying duty or for interrupting duty.  The 

position of the ground making contacts can be 

observed when the device is in the switchgear 

compartment through transparent viewing 

panels 

(Figure 1, e)

 in front of the contacts.