Article 4.19.1C : Ates DG to EB change over not happening.
By default our ATEs over voltage is configured to 260v. If EB voltage more than 260v then change over issue will come in to picture. so we required to change EB over voltage to 265 or 270 V then problem will resolve. Other customer should reduce there incoming voltage at transformer side less then 260 V .
To change over voltage customer required remote unit.