UPS Electrical Installation
Liebert
®
e
XL
™
14
2.5
Grounding
2.5.1 Three-Wire Input connections
This module must NOT be used when single-phase loads are directly connected to the UPS. Note that
whenever the UPS module transfers to or from bypass, two AC sources (UPS output and bypass) are
briefly connected together and circulating current must flow. In this configuration, the current flows
through the ground path and may trip ground fault interrupters (GFI’s), distorting the output voltage
waveform. Proper adjustment of GFI’s is necessary to avoid unwanted tripping. The time delay
should be set to at least 0.2 seconds to prevent tripping when the UPS performs a transfer or
retransfer operation.
NOTICE
Failure to set the ground fault interrupters properly could cause loss of power to the critical
load.
2.5.2 High Resistance Grounding
Contact your Emerson
®
representative or the factory to determine whether the Liebert eXL is
compatible with the specific type of HRG system involved.
2.5.3 Preferred Grounding Configuration, Battery Systems
Open-rack battery systems, depending on local code requirements and customer preference, are
normally:
• Floating (ungrounded) OR
• Center-tapped and floating
Battery cabinet systems must be connected as floating (ungrounded) systems.
Center-tapped or grounded battery systems are not possible with battery cabinet systems.
Whether the battery system is open-rack or cabinet, the metal rack parts or cabinet must be grounded
to the UPS module ground bus.
Table 3
UPS control contacts to Battery Interface Boards
Item
Terminal
Block
Pin
Connects to
(Description of
External Item)
Maximum
Voltage
Maximum
Current
Wire
Range
Maximum
Length
Battery Cabinet
Communication
TB1154
1
CAN +24V
24VDC
2A
18AWG
1000ft
(305m)
2
CAN Common
3
CANbus High
4
CANbus Low
1. To prevent signal interference, low voltage (<48V) and low current (5A) cable groups should be run in separate grounded
conduit from high voltage or high current cable groups.
2. All external wire furnished by others.
3. All wiring must be in accordance with national and local electrical codes.
4. The maximum length must take into account all battery communications connections in the system.
Table 4
UPS control contacts to Remote Status Panel
Item
Terminal
Block
Pin
Connects To
(Description of
External Item)
Maximum
Voltage
Maximum
Current
Wire
Range
Maximum
Length
Remote Status Panel
TB1
1
CAN +24V
24VDC
150mA
18AWG
1000ft
(305m)
2
CAN Common
3
CANbus High
4
CANbus Low
1. To prevent signal interference, low voltage (<48V) and low current (5A) cable groups should be run in separate grounded
conduit from high voltage or high current cable groups.
2. All external wire furnished by others.
3. All wiring must be in accordance with national and local electrical codes.
