Maintenance switch
The purpose of the main switch input is to allow a controlled shut-down and restart procedure of the outputs. Typically, contacts from a local isolator next to the fan motor will be used. When the local isolator is switched off, the input "MaintSw" will be 0 and the outputs "ST1Cmd" and "FanSpeedControl" will be switched off without delay. When the maintenance switch becomes 1 again, the plant can be restarted.
The maintenance switch will generate a alarm at the "OffAlarm" output.
With the parameter ALM-01 the user can change the contact type of the maint. switch to NO (normally open) or NC (normally closed).
Description |
Default value |
ALM-01: maint switch NO/ NC; 1 = NC |
1 |
ALM-02: maint switch reset type 0 = manual reset 1 = auto reset |
1 |
Manual- or automatic reset
After switching back the maintenance switch, a reset is required.
The user can with parameter ALM-02 choose between manual or automatic reset.
In case of manual reset, the user has to connect the Reset input of the macro to the reset button.