User guide

A120 Power Supplies
890 USE 108 00 August 2001 189
Overload and
Overvoltage
Protection
Should the supplies lose regulation they have internal over voltage protection that
prevents the output from exceeding 35 V. If an over voltage condition is sensed the
modules will shut down and will not restart until the AC or DC input source has been
turned off for a minimum of 5 minutes.
LED Indicators These power supplies have two indicator LEDs, one green and one red. The green
LED is located on the AC line source side and, when on, indicates that the power
supply is running properly with AC line input present. The red LED, located on the
DC battery power input side indicates, when on, that the supply is running on the
user supplied DC source (battery), and that the AC line input is not present. The
indicator LEDs will not be on at the same time.
Battery Backup In the event of a primary power outage the Compact system continues to operate on
the user supplied battery backup and a 24VDC (12mA max.) power lost signal is
generated. This power lost signal may be monitored using a discrete input module
or other method per the user requirement. Battery support time is dependent upon
the Compact system power requirement and the capacity of the user supplied
battery.
Note: It is not recommended that the same power supply be used to power both
the Compact 984 and its I/O.
Separate supplies are recommended to reduce the risk of field noise affecting the
controller’s operation. In cases of single supply configurations a field point failure
could cause the power supply, and so the controller, to shut down.