086406-002 ABB Controller module motor card inventory

Description

The characteristics of the utilization categories are detailed in Table 1 below.
The most demanding category in alternating current is AC23A, for which the
device must be capable of connecting a current equal to 10 times the rated
current of the device, and of disconnecting a current equal to 8 times the rated
current of the device.
From the point of view of construction, the switch disconnector is a very simple
device. It is not fitted with devices for overcurrent detection and the consequent
automatic interruption of the current. Therefore the switch disconnector cannot
be used for automatic protection against overcurrent which may occur in the
case of failure, protection must be provided by a coordinated circuit-breaker.
The combination of the two devices allows the use of switch disconnectors in
systems in which the short-circuit current value is greater than the electrical parameters which define the performance of the disconnector (back-up protection
see Chapter 3.4. This is valid only for Isomax and Tmax switch-disconnectors.
For the Emax/MS air disconnectors, it must be verified that the values for Icw
and Icm are higher to the values for short-circuit in the plant and correspondent
peak, respectively