LA Software Modifications

Two modifications have been made to the LA software which can be used to change some basic functions by selecting non-default settings. These settings are:

• Arming Mode – for a Tie

• Pickup – for Feeder and Mid-Point devices

These settings can only be changed via WSOS on the LA Display page when the Protection password is active.

Display > LA > Display

To guard against either of these settings being changed accidently, WSOS displays the message below if they are selected:

These settings also appear on the operator interface but cannot be changed, that is they are read-only.

The Arming Mode setting for Tie devices defaults to Default which is the setting required for normal LA operation.

The alternate setting is Alternate which modifies the operation of the Tie device when selected.

The Tie normally requires the voltage on its source and load terminals to be either both Dead or both Live before it will respond to a loss of supply.

Selecting Alternate for the Arming Mode will effectively ARM LA at the time it is turned on, without waiting for the conditional state of Live-Live or Dead-Dead on the Tie terminals.

The Pickup setting for Feeder and Mid-Point devices defaults to Blocks Trigger which is the setting required for normal LA operation.

The alternate setting is Allows Trigger which modifies the operation of the Feeder and Mid-Point devices when selected.

In normal operation, LA is suspended when a protection pickup occurs.

Setting Allows Trigger for the Pickup setting helps to ensure that fault protection and voltage sensing for LA remain independent and each will continue to operate regardless of the operation of the other. In other words, LA will continue to operate even when a protection pickup is active.