58 Chapter 7 Parallel System And Dual Bus System
APM 300 Integrated UPS Single Module And Parallel System User Manual
The dual bus system uses the LBS to keep the output of the two independent UPS systems (or parallel systems)
in synchronization. One system is designated as the master, the other is designated as the slave. The operation
modes of the parallel system comprise master and/or slave operation in normal or bypass mode.
Place the UPS modules side by side and interconnect the UPS modules according to the following instructions.
7.4.2
External Protective Device
Refer to
3.1.7 External Protective Device
.
7.4.3
Power Cable
The wiring of power cables is similar to that of single module system. See
3.1 Power Cables
.
The bypass and the main input sources must be referenced to the same neutral potential, and the input earth
leakage monitoring devices, if installed, must be located upstream of the common neutral sinking point.
7.4.4
Control Cable
For a dual bus system composed of two APM UPSs, connect the optional LBS cables between the two UPS
systems as shown in Figure 7-6 to Figure 7-8. The J3 and J4 ports are provided on the front panel of the bypass
module, as shown in Figure 7-3.
UPS 1
Bypass module
LBS cable
UPS 3
UPS 4
J2
J3
J4
J2
J3
J4
J2
J3
J4
J2
J3
J4
Bypass module
Bypass module
Bypass module
UPS 2
LBS cable
UPS 1
UPS 2
UPS 3
UPS 4
Bypass module
Bypass module
Bypass module
Bypass module
J2
J2
J2
J2
J3
J3
J3
J3
J4
J4
J4
J4
LBS cable
LBS cable
Figure 7-6
Connection of typical dual bus system of two parallel systems
UPS 1
Bypass module
LBS cable
J2
J3
J4
J2
J3
J4
Bypass module
UPS 2
UPS 1
UPS 2
Bypass module
Bypass module
J2
J2
J3
J3
J4
J4
LBS cable
Figure 7-7
Connection of typical dual bus system of two single UPSs without redundancy LBS cable
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