Set up generator auto start and stop

Scope

Generator auto start and stop is a rule list that opens and closes the generator start relay. The rules use the battery state of charge. See Build a rule list and What a rule condition can read field definitions.

Location

Path: My Devices, Plant Control System, then the Diagram tab.
Settings: in the three-dot menu of the diagram, set Edit to on. Then double-click the generator point.

Permissions

See the settings: all access levels. A Viewer double-clicks a device on the diagram and sees its settings without the Save button.
Change and save the settings: Editor, Installer or Full control.

Step 1: Start Relay

On the Basic tab, set Rated Power to the rating of the generator connection. Do not set 0.
Set Output ID to the logger output that operates the start relay.

Step 2: Rule List

On the On/Off State tab, add these rules in this order:

Order	Condition	Value
1	Storage % > stop level	Off
2	Storage % < start level	On
3	Fixed Value 1 > Fixed Value 0	Do Nothing

Stop level: higher than the start level.
Must hold for: on rule 2. Thus a short decrease of the state of charge at high load does not start the generator.
Do Nothing: on rule 3. Between the two levels, rule 3 wins and keeps the last value.
Default: Off.

The On/Off State tab with a stop rule, a start rule and a Do Nothing rule

Step 3: Save

Examine all rules before you click Save. The logger applies the rules at the next control cycle and starts or stops the generator with no confirmation step.

Click Save at the bottom of the dialog.

Step 4: Manual Override

Make a user variable. See Set up System Variables.
Above rule 1, add System Variable = 0 with the value Off.
Below it, add System Variable = 1 with the value On.

Other values give the automatic rules. An override stays until somebody changes the variable.

The same list with two manual override rules above the automatic rules

Troubleshooting

The generator starts and stops again and again: the two levels are equal, or rule 3 is missing.
The generator does not stop: a rule above the stop rule is true first. The rule that wins is green.
Nothing happens: set Enabled to Enabled on the Basic tab. Set Totals Calculation to Include on the Advanced tab, because Exclude also stops the generator. Then examine Output ID.
The generator runs while the list shows false: the app cannot invert the start output. Examine the relay wiring.

Tips and Gotchas

The list shows On as true, Off as false, and Do Nothing as Previous Eval.
The first rule that is true wins. To keep the generator off while grid power is available, put a grid Off rule above the low-battery On rule.