Issue
Incorrect Line Voltage measurement transmitted over Modbus communication.

Measurement is transmitted as 6.9kV instead of actual 6.6kV

On Relay Display
Module UAB : 6.52
Module UBC : 6.48
Module UCA : 6.52

On Modbus Address by Modscan tool
Module UAB : 6.9
Module UBC : 6.9
Module UCA : 6.9

Module UAB (Modbus address) >> 0088
Module UBC (Modbus address) >> 0089
Module UCA (Modbus address) >> 008A


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Product Line
MiCOM P127

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Environment
Normal

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Solution
Module UAB, UBC & UCA (HEX 88,89,8A) data unit is CAN.

Value (Unsigned integer) available at these address are not direct measurement value instead it is CAN values. User has to use below formula given in the manual to arrive at the actual measurement.

Line voltage value (primary value) = value x (phase primary VT ratio / phase secondary VT ratio) / 63

6.9 x ((6600/110) / 63) = 6.9 x 0.95 = 6.57 --> Now the relay HMI measurement is matching approximately.
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*Warning:  Installation, maintenance, up-gradation, down-gradation of MiCOM device should only be performed by qualified, competent personnel that have appropriate training and experience. Failure to follow the instructions / warnings in the Installation / Operation Guide can result in unwanted disruption to the power system, permanent damage to the device, severe injury or death.*

Released for:Schneider Electric India