Instruction Book
Effective: February 2007
Page 43
I.B. 8295A61H07
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SECTION 7: INSPECTION AND
MAINTENANCE
7-1 INTRODUCTION
WARNING
•
DO NOT WORK ON A BREAKER IN THE
“CONNECTED” POSITION.
•
DO NOT WORK ON A BREAKER WITH
SECONDARY DISCONNECTS ENGAGED.
•
DO NOT WORK ON A BREAKER WITH
SPRINGS CHARGED OR CON TACTS
CLOSED.
•
DO NOT DEFEAT ANY SAFETY INTERLOCKS.
•
DO NOT LEAVE MAINTENANCE TOOL IN
THE SOCKET AFTER CHARGING THE
CLOSING SPRINGS.
•
DO NOT STAND LESS THAN ONE METER
AWAY FROM THE BREAKER WHEN TESTING
FOR VACUUM INTEGRITY.
FAILURE TO FOLLOW ANY OF THESE
INSTRUCTIONS MAY CAUSE DEATH, SERIOUS
BODILY INJURY, OR PROPERTY DAMAGE. SEE
SECTION 2-SAFE PRACTICES FOR MORE
INFORMATION.
7-2 FREQUENCY OF INSPECTION
Inspect the breaker every 12 to 18 months when
operating in a clean, non corrosive environment. For a
dusty and corrosive environment, inspection should be
per-formed twice a year. Additionally, it is recommended
to inspect the breaker every time it interrupts fault
current.
Refer to the table on the following page for maintenance
and inspection check points.
7-4 VACUUM INTERRUPTER INTEGRITY TEST
Vacuum interrupters used in Type VCP-WR circuit
breakers are highly reliable interrupting elements.
Satisfactory performance of these devices is dependent
upon the integrity of the vacuum in the interrupter and
the internal dielectric strength. Both of these parameters
can be readily checked by a one minute ac high
potential test. (See Table
7.1
for appropriate test
voltage.) During this test, the following warning must be
observed:
CAUTION
APPLYING ABNORMALLY HIGH VOLTAGE ACROSS
A PAIR OF CONTACTS IN VACUUM MAY PRODUCE
X-RADIATION. THE RADIATION MAY INCREASE
WITH THE INCREASE IN VOLTAGE AND/OR
DECREASE IN CONTACT SPACING. X-RADIATION
PRODUCED DURING THIS TEST WITH
RECOMMENDED VOLTAGE AND NORMAL CONTACT
SPACING IS EXTREMELY LOW AND WELL BELOW
MAXIMUM PERMITTED BY STANDARDS. HOWEVER,
AS A PRECAUTIONARY MEASURE AGAINST
POSSIBILITY OF PPLICATION OF HIGHER THAN
RECOMMENDED VOLTAGE AND/OR BELOW
NORMAL CONTACT SPACING, IT IS RECOMMENDED
THAT ALL OPERATING PERSONNEL STAND AT
LEAST ONE METER AWAY IN FRONT OF THE
BREAKER.
With the breaker open and sitting solidly on the floor or
secured in a fixed position, connect all top primary studs
(bars) together and to the high potential machine lead.
Connect all bottom studs together and ground them
along with the breaker frame. Start the machine at zero
potential, increase to appropriate test voltage and
maintain for one minute.
Successful withstand indicates that all interrupters have
satisfactory vacuum level. If there is a breakdown, the
defective interrupter or interrupters should be identified
by an individual test and replaced before placing the
breaker in service.
After the high potential is removed, discharge any
electrical charge that may be retained, particularly from
the center shield of vacuum interrupters. To avoid any
ambiguity in the ac high potential test due to leakage or
displacement (capacitive) current, the test unit should
have sufficient volt-ampere capacity. It is recommended
that the equipment be capable of delivering 25
milliamperes for one minute.
Although an ac high potential test is recommended, a dc
test may be performed if only a dc test unit is available.
T a b l e 7 . 1 T e s t V o l t a g e
V a c u u m I n t e r r u p t e r I n t e g r i t y T e s t V o l t a g e
B re a k e r R a te d
Ma x i mu m V o l ta g e
ac 60 H
dc
Up to and including
15.0 kV
24 and 27 kV
27kV
45kV
40kV
45 kV
Содержание Cutler-Hammer VCP-WR Series
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