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16.0 M
AINTENANCE
WARNING
!
Only qualified service personnel should perform maintenance on the STS2/PDU.
Lethal voltages exist inside the unit during normal operation.
The unit is supplied by multiple AC power sources. Disconnect and lock out all power sources
before working inside unit.
Minimal periodic maintenance of the STS2/PDU is required. As with all electrical distribution compo-
nents, the system should be regularly inspected for electrical connection integrity, signs of excessive
temperatures, dirt accumulation and proper system operation.
16.1
Proper Tightening of Nuts and Bolts
The recommended tightening torque for all nuts and bolts is as shown below, unless otherwise
labeled. All power connections are designed to remain at proper torque throughout the lifetime of the
unit.
Table 29
Torque tightening
Bolt Shaft Size
10-32
1/4-20
5/16-18
3/8-16
1/2-13
Table 30
Branch circuit breakers
Current Rating
Up to 30 Amp
40 to 100 Amp
16.2
Testing the STS2/PDU
The STS2/PDU includes comprehensive system alarms and fault detection to identify operational
problems. To increase the degree of confidence of proper system operation, periodic transfer tests can
be easily performed. For instructions for changing the preferred source and switching sources, see
10.2 - Manual Transfer / Preferred Source Selection.
16.3
Changing the Air Filter
A standard furnace filter is installed behind the air intake in the front door. The air intake allows air
to circulate to cool the unit. Replace the filter when it becomes dirty and impedes air flow. The fre-
quency of changing or cleaning the filter depends on the location in which the unit is located. The size
of the filter is 1 x 25 x 25 in. (254 x 635 x 635mm).
Grade 5 - Imperial
Grade 8.8 - Metric
in-lb
N-m
(pound-inch)
(Newton-meter)
25
53
107
192
428
in-lb
N-m
(pound-inch)
(Newton-meter)
35
45
Electrical Connections with
Belleville Washers
in-lb
(pound-inch)
3
35
6
80
12
180
22
240
48
480
4.0
5.1
144
Maintenance
N-m
(Newton-meter)
4
9.0
20.4
27.1
54.3
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