The LHMI keypad on the left side of the protection relay contains 16 programmable push buttons with red LEDs.
The buttons and LEDs are freely programmable, and they can be configured both for operation and acknowledgement purposes. That way, it is possible to get acknowledgements of the executed actions associated with the buttons. This combination can be useful, for example, for quickly selecting or changing a setting group, selecting or operating equipment, indicating field contact status or indicating or acknowledging individual alarms.
The LEDs can also be independently configured to bring general indications or important alarms to the operator's attention.
To provide a description of the button function, it is possible to insert a paper sheet behind the transparent film next to the button.