Maintenance
High Speed Moving Parts. Can cause
serious injury.
Tripping spring is charged. If trip latch is
moved, the stored energy springs will dis-
charge rapidly.
Avoid physical contact with circuit breaker
parts subjected to sudden, high speed move-
ment.
Hazardous voltages and high-speed
mechanical parts.
Will cause death, severe personal injury, or
property damage.
De-energize before working on this
equipment.
Read instruction manuals, observe safety in-
structions and limit use to qualified person-
nel.
18
4.76kV 31.5kA 31.5kA B 6
4.76kV 40kA 40kA C 7
4.76kV 50kA 50kA C 11
8.25kV 40kA 40kA C 7
15kV 20kA 20kA A 1
15kV 25kA 25kA B 5
15kV 31.5kA 31.5kA B 6
15kV 40kA 40kA C 7
15kV 50kA 50kA C 11
27kV 25kA 25kA A 2
38kV 31.5kA 31.5kA D 12
Table 3.
Typical Vacuum Interrupter Contact Life Expectancy
Graph Curve
Rated Max.
Voltage
Interrupting
Class
Rated
Current
Curve Number
4.76kV 250MVA 36kA A 3
4.76kV 350MVA 49kA C 10
8.25kV 500MVA 41kA C 8
15kV 500MVA 23kA B 4
15kV 750MVA 36kA A 3
15kV 1000MVA 48kA C 9
38kV 1500MVA 35kA D 13
4. Press the red Trip pushbutton after completing the con-
tact erosion check. Visually verify the Discharge con-
dition of the closing springs and that the circuit breaker
contacts are Open.
5. Press the black Close pushbutton. Nothing should hap-
pen. The manual spring check should demonstrate
smooth operation of the operating mechanism.
Electrical Control Checks
The electrical controls of the 3AH circuit breaker should be
checked during inspections to verify absence of any me-
chanical damage, and proper operation of the automatic
spring charging and Close and Trip circuits.
Unless otherwise noted, all of these tests are performed
without any control power applied to the circuit breaker.
Check of the Wiring and Terminals
1. Physically check all of the breaker wiring for evidence
of abrasion, cuts, burning or mechanical damage.
2. Check all terminals to be certain they are solidly at-
tached to their respective device.
Automatic Spring Charging Check
(Control Power Required)
Repeat the automatic spring charging check described in
the section entitled Installation Checks and Initial Functional
Tests.
Primary tasks of this check are:
1. The breaker is energized with control power for this
check.
2. Energize the control power source.
3. When control power is connected to the circuit breaker,
the closing springs should automatically charge. Vi-
sually verify that the closing springs are charged.
Note: A temporary source of control power and test leads
may be required if the control power source has not been
connected to the switchgear. When control power is con-
nected to the 3AH circuit breaker, the closing springs should
automatically charge.
To Next Page
Loading...
