Chapter 7 - 1+1 Parallel System; Generality - Liebert 7200 Series User Manual

7200 Series UPS User Manual
Single Module and 1+1 Parallel System
7.

Chapter 7 - 1+1 Parallel System

7.1

Generality

The system consist of two single UPS 7200 modules with the same power rating. Each UPS is equipped
with the optional parallel Kit (part no. 4645004A), and the outputs to the load are connected in
parallel.
The system can be configured on site as follows:
• redundant parallel
• power parallel (available with software revision V4.1 and subsequent revisions and High-Voltage
Interface board part no. 4590058S)
Redundant parallel
A system is defined a being in a redundant parallel configuration when the load power rating is less than
or equal to the rated power of are UPS module. In this case, only one UPS is needed to supply the load.
Normal operation
◊
Both the UPS units supply the load. They automatically share current and are synchronised with to
the mains. They remain synchronised to each other during a power outage and are synchronised
again with the mains when power is restored.
◊ Fault or manual inverter shutdown
The load continues to be supplied by the inverter of the second UPS.
◊ Overload
The system has a very high overload capacity, equal to the sum of the power ratings of the two UPS
units plus the relative overload (minimum three times the supplied load). If the power demanded by
the load temporarily exceeds this value, the load switches to the mains bypass through both UPS
modules.
◊ Maintenance
Maintenance can be performed on a UPS by opening the relative switches without using the
internal manual By-pass, since the second UPS can supply the load.
Power parallel
A system is defined a being in a power parallel configuration when the power requested by the load is
greater than the rated power of one UPS module. In this case, both UPS modules are needed to supply
the load.
◊ Normal operation
Similar to the redundant parallel configuration.
◊ Fault or manual Inverter shutdown
The load is switched to the mains bypass through the Static Switches of both UPS modules, even if
the power requested at that time by the load is less than the power rating of one UPS.
◊ Overload
The overload capacity is equal to 1.5 times the system power rating.
◊ Maintenance
To carry out maintenance operations, both UPS modules must be switched to manual bypass.
Battery configuration
The system is designed to operate with two different battery configurations:
◊ With separate batteries
Each UPS is connected to its own battery (see figure 7-1).
This is the most common configuration.
◊ With common battery
The two UPS units are connected to a single battery (see figure 7-2).
The option "Battery auxiliary distribution box" (see paragraph 7.4) is required for common battery.
document in response to "powersure ups"
Chapter 7 - 1+1 Parallel System
Generality
Page 7-1
Issue 6
(03/98)