20
S&C Instruction Sheet 775-510
For the convenience of users who normally perform
electrical tests on system components such as Scada-Mate
SD switches, appropriate withstand test values are given
in Table 1. These test values are significantly greater than
the normal operating voltage of the Scada-Mate SD switch
and are near the flashover voltage of the equipment. They
should be applied only when the Scada-Mate SD switch is
completely de-energized and disconnected from all power
sources.
WARNING
The following test procedures must be performed
by qualified persons who are knowledgeable in the
installation, operation, and maintenance of overhead
electric power distribution equipment along with the
associated hazards .
DANGER
When performing electrical withstand tests on Scada-
Mate SD Switching Systems, observe the following
precautions:
1 . Completely de-energize the Scada-Mate SD switch
and disconnect the phase conductors from all six
terminal pads . If the Scada-Mate SD switch is
supplied with the optional wildlife protection feature
(catalog number suffix “-W”), slide the tap cover
back far enough to gain access to the terminal pads .
Then, remove the upper and lower terminal-pad
covers to permit the removal of the phase
conductors . Retain the covers for reinstallation at
the conclusion of the test .
2 . At each of the six terminal pads, disconnect the
leads for the surge arresters . Make sure the surge
arrester leads are tied back so they are at least
8 inches (203 mm) from any terminal pad .
3 . Open the Scada-Mate SD switch interrupters
manually by using a hookstick to pull down on the
OPEN lever . For disconnect-style models, close
the hookstick-operated disconnects .
Failure to observe these precautions can result in
a flashover, injury, and equipment damage.
Dielectric Testing
Table 1. Withstand Test Voltage
Rating, kV
Withstand Test Voltage, kV
Nom.
Max.
60-Hz, RMS
①②
Dc
Impulse (BIL)
14 .4
17
32
45
110
25
29
52
74
125
●
①
The 14 .4-kV test values are limited by the internal sensor spark-gap
rating .
②
The 25-kV test values are approximately 75% of the design values .
●
Refer to Table 2 .
Table 2. 25-kV Scada-Mate SD Switch BIL Ratings
Without Optional
Disconnect
With Optional Disconnect
Vacuum
Interrupter
BIL
Vacuum
Interrupter
Optional
Disconnect
BIL
Closed
150 kV
Open
Open
150 kV
Closed
Closed
150 kV
Open
125 kV
Open
Closed
125 kV
