American Power Conversion Symmetra MW - Manual (Page 40)

Specifications: Required Breaker Settings
36 Symmetra MW 1000 kW 480 V Installation - 990-4112E
18 kA is the maximum peak let-through current (including safety factor) available during clearing of
an internal fault in a 200 kW section or a Power Module. During or after a controlled fault clearing,
none of the breakers are allowed to trip on the instantaneous trip setting below the specified value.
This is also applicable to the upstream breakers, and a control of the instantaneous trip setting in this
part of the installation is required. The maximum peak let-through current is applicable to utility with
prospective short-circuit currents up to 200 kA.
The following diagram shows a dual utility system in which the upstream breakers are named Q.
Correct settings of upstream breaker settings are mandatory. The system can also be configured as a
single utility system.
Note
The instantaneous trip setting must not be derated even though the UPS system is derated
in system output power. The system size has no influence on the instantaneous trip
setting.
Note
For derated systems, the APC Application Team provides the correct breaker settings and
breaker frame sizes.
Note
For upstream breakers not mentioned in the table, the APC Application Team provides
the correct breaker settings for on-line, overload, and trip currents.
Q1
Q3
Q5
Q4 Q2
Q6
Q
Q
T1
T2
Dual Utility Installation