The Model 541 Protection Expansion/Annunciator is designed to be used as either a protection expansion module, an annunciator, or a combination of both. The inputs are fully configurable by the user to suit the application. The module features a number of facilities enabling it to be used
as a stand alone module or part of a complex control system. It is particularly suited to providing input expansion to the DSE 500 series control modules.

The Safety On timer can be selected to be either internal from the Fuel On input being active, or externally fed from another device such as the 520 Automatic Start module. An Alarm Reset input is provided to
enable the alarms to be cleared. This can be configured to be fed from either plant negative or plant positive DC. This gives maximum flexibility to the module, and allows for interfacing with an output
relay on a 520 to enable the 520 module control switch to be the master alarm clear control.

The module also features plant DC supply monitoring alarms and can provide indication of a high or low supply voltage. This feature can be disabled if not required. Alterations to the system are made by
using a PC and the 808 interface. This also provides the operator with real time diagnostic facilities to monitor the system.