37
11.6 Grounding configuration
This section describes the grounding configuration with AC input service entrance.
As inadequate grounding configuration causes problems on start-up, connections for the ground line
and the neutral line must be done properly according to the system configuration.
11.6.1 Recommended configuration with input neutral grounded
Figure 11.8 shows recommended grounding configuration with input neutral grounded.
The neutral line at the input source is usually grounded. The neutral terminal in the UPS cabinet should
be open, as the neutral line must be grounded only at one point in a system. And the neutral line must
be properly fed to the bypass input.
Figure 11.8 - Grounding configuration with input neutral grounded.
A jumper cable of 2AWG (or 38mm
2
) is provided between the neutral terminal and ground bus in the
UPS cabinet. Notice that the electrical contractor should unscrew and disconnect the jumper cable in
this configuration. The cable location is illustrated below.
Figure 11.9 - Jumper cable between the neutral terminal & ground bus.
N
G
3
φ
3
φ
3
φ
N
G
< UPS Cabinet >
N
3
φ
3
φ
G
Input Source
Disconnect
The Cable
Ground
Bus
Neutral
Terminal
Disconnect
Jumper
Cable here
< 100~225kVA >
Ground
Bus
Disconnect
Jumper
Cable here
< 250/300kVA >
Neutral
Terminal
G
N
3
φ
To the
Load
