APC MW II manual Output and downstream breakers

Output and downstream breakers

Q2, Q4, Q6

Duration [S]	Current [A]	Total load [%]	Event/Operation
< 0.005	22 kA	--	Internal fault clearing.
60	3464*	200	Overload on-line
600	2165*	125	Overload on-line
∞	1732	100	On-line

* In the absence if a coordination study conducted by a professional engineer, the recommended

instantaneous trip setting for breakers Q1, Q2, Q4, Q5, and Q6 is 22 kA

** Only applicable to Q2 and Q4

In the absence of a proper breaker coordination study and if only the actual Ip on the unit’s input terminals is known, this table must be used to optimize the instantaneous trip setting or to choose a breaker with a usable fixed instantaneous trip value.

Ip* [kA]	I peak let-through [kA]	I setting [kA]
200	16	18
140	14	16
100	13	15
50	10.5	12
30	9	11

* Ip = Abridgment for Prospective short-circuit current.

This is the current that would flow in the fault circuit is the fuse was

replaced by a link with an infinitely small impedance

22 kA is the maximum peak let-through current (including safety factor) present during clearing of an internal fault in a 200 kW section or a power module. This maximum peak let-through current is based on and applicable to utility with prospective short-circuit currents (Ip) up to 200 kA.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 check of the instantaneous trip setting in this part of the installation is required.

The instantaneous trip setting calculated by a professional engineer in a breaker coordination study must not disable the functionality of clearing and surviving an internal fault unless there is a written agreement between APC by Schneider Electric and the customer.

By ensuring the unit’s fault clearing ability (survival skills) i.e. using the correct instantaneous trip settings in the switch gear (installation), maximum power availability in normal operation is obtained for the critical load.

Note: The instantaneous trip setting can be calculated when utility Ip is known. An incorrect trip setting can result in limiting the system functionality and jeopardize the load support.

Symmetra MW II 1200 kW 3 x 400/230 V Installation - 990-1979E-001 21