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4.4.2 Torque Requirements
All electrical connections must be tight. Table 10 provides the torque values for the connections in
the UPS. Use these values unless the equipment is labeled otherwise.
4.5 Detection of Trouble
It is important that the operator check the instrument readings if abnormal equipment performance
is suspected. Any metered value that differs appreciably from normal could mean an impending mal-
function and should be investigated.
Items to check include:
• Output voltage of all phases should be within 2% of normal voltage. Output currents on each
phase should not normally differ by more than 20%. If a greater difference is noted, the load is
unbalanced and corrective action should be taken to redistribute the load, if possible.
• If the UPS has not operated on battery power during the last 10 hours, the batteries should
require little charging current. Battery mimic should indicate normal DC voltage with the battery
charge current no more than 1% of maximum discharge current.
• Input current on each phase should be within 10% of the average input current.
• Alarm messages indicate malfunction or impending malfunction. A daily check of the Operator
Control Panel will help to provide an early detection of problems. Refer to Table 4 and Table 5 to
interpret alarm messages.
• Tracing a problem to a particular section is facilitated by alarm messages and the metered
parameter indications. These are stored in the Status Reports and can be displayed at the Opera-
tor Control Panel or at an optional terminal. A Liebert Global Services engineer will be familiar
with test points inside the unit.
NOTE
Refer to the battery manufacturer’s manual, available on the manufacturer’s Web site, for the
proper torque values required for the battery.
Table 10 Torque specifications (unless otherwise labeled)
Nut And Bolt Combinations
Bolt Shaft Size
Grade 2
Standard
Electrical Connections
with Belleville Washers
Lb-in N-m Lb-in N-m
1/4 53 6.0 46 5.2
5/16 107 12 60 6.8
3/8 192 22 95 11
1/2 428 48 256 29
Circuit Breakers with Compression Lugs (For Power Wiring)
Current Rating Lb-in N-m
400 - 1200 Amps 300 34
Circuit Breakers with Compression Lugs (For Control Wiring)
AWG Wire Size or Range Lb-in N-m
#22 - #14 3.5 to 5.3 0.4 to 0.6
NOTE
If the UPS system has a blown fuse, determine the cause should be determined before replacing
the fuse. Contact Liebert Global Services for assistance.