14
Replacement of Cover Gasket for Padmount Switchgear Side-Hinge-2 Models
Field Service inStructionS
MN285009EN April 2019
12.2 Verify that the air-pressure supply/air compressor
supply is equipped with a desiccant air dryer installed
inline (Figure 64).
NOTICE
Equipment damage . Failure to use an air dryer
while pressurizing the system may result in water
contaminating the dielectric fluid in the switchgear .
Standard with
polycarbonate bowl
Standard with
aluminum bowl
Figure 64.
Examples of typical desiccant air dryers
12.3 Pressurize the system:
12.3.1 With the ball valve turned off, attach the
air-pressure supply to the end fitting of the
leak-test assembly.
12.3.2 Slowly open the ball valve to pressurize the
tank to 7.25 psig; then shut off the valve.
12.3.3 Wait five minutes for internal-to-external
temperature equalization.
12.3.4 Check the pressure at the end of the five-
minute temperature-equalization period.
If the pressure dropped below 7.25 psig while
the temperature equalized, slowly re-open the
ball valve to bring the pressure back to 7.25
psig. Then shut off the valve.
12.4 Let the tank sit for 30 minutes with the starting air
pressure at 7.25 psig.
12.5 After waiting at least 30 minutes, check to see if the
pressure was maintained:
●
●
If the pressure dropped below 7 .25 psig:
The tank
is leaking. Find and stop the leaks as directed in
step 12.6.
●
●
If the tank maintained a pressure of 7 .25 psig
for
the 30-minute test period, the tank passed the leak
test. In that case, continue to step 12.7.
12.6
If necessary:
Find and stop leaks:
12.6.1 Obtain a Microsonic Detector Model EI-701
sonic leak detector (Figure 65) or equivalent.
ote:
N
You can also use a soap solution such
as “SNOOP” to help find air leaks.
Figure 65.
12.6.2 Verify the function of the sonic detector by
opening the pressure-relief valve and pulling
the trigger on the detector.
The needle should jump from 0 (Figure 66) to
100 (Figure 67) while the relief valve is open.
Figure 66.
Detector at zero (relief valve closed)
Figure 67.
Detector at 100 (relief valve open)
12.6.3 Set the sonic meter’s sensitivity dial to 10
(Figure 68); then perform an initial pass to
determine if the unit is leaking (Figure 69).
