Liebert PDUTM Proper Tightening of Nuts and Bolts, Testing the STS2/PDU, Changing the Air Filter

Maintenance

16.0 MAINTENANCE

! 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.

16.1Proper 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

	Grade 5 - Imperial		Electrical Connections with
	Grade 8.8 - Metric		Belleville Washers
	in-lb	N-m	in-lb	N-m
Bolt Shaft Size	(pound-inch)	(Newton-meter)	(pound-inch)	(Newton-meter)
10-32	25	3	35	4
1/4-20	53	6	80	9.0
5/16-18	107	12	180	20.4
3/8-16	192	22	240	27.1
1/2-13	428	48	480	54.3

Table 30 Branch circuit breakers

	in-lb	N-m
Current Rating	(pound-inch)	(Newton-meter)
Up to 30 Amp	35	4.0
40 to 100 Amp	45	5.1

16.2Testing 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.

16.3Changing 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).

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