PowerLogic T300 - issue ready analog data from a PowerLogic P3

John_Archer1 · ‎2024-11-22

The analog value I am reading has a minus sign (-) and an incomplete value. What settings am I making a mistake in? Has anyone had this problem? I am

Read setting t300IEC101 settingP3 Line voltage Measured valueP3 scale settingT300 Reading voltage view webserver

Mathieu_Lansoy · ‎2024-12-12

Hello,

In standard, MMEB format should transmit signed 16 bits values, so from -32768 to + 32767.

These measurements will be managed in this format by the T300 if they're declared as MMEB.

Apparently, the P3 uses unsigned 16 bits, from 0 to 65536 and does not scale down the values.

If the value is less than 32767, no issue. If the value is higher than 32767, most significant bit of the 16bits format will be set, and treated as a negative sign by the T300.

Ex: 33933 V -> 0x848D -> -31603 (signed 16 bits).

This explains the values shown on the T300 webapp.

If no scaling system can be found on the P3, we can use Formulas on the T300 to correct the value by adding 65535 to the negative values.

another idea: use the "normalized" (MMEA) format proposed by P3 (but i don't know how the conversion is done in this case, maybe using the corresponding "Max" setting that can be seen on the "IEC 60870-5-101: AI" page.

regards,

Mathieu.

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sathishkumar_ramakrishnan · ‎2024-12-02

Hello John Archer,

In MMEB the value stored in coreDb is converted in a 16-bit entire signed value. So once it exceeds the 16 bit range,it throws the negative value. Hence you need to change the phase voltage AB, BC and CA data type as MMEC which is 32 bit floating value has wide range.

If you want to use the data type as MMEB only, then you need to scale down the value to 16 bit range.

Regards,

Sathish

John_Archer1 · ‎2024-12-04

@sathishkumar_ramakrishnan Thanks for the reply. The Easergy Rele I am using only reads MMEB values. How do I change 32 bit to 16bit?. Also, the measurement format is not normalized and does not transmit analog information at all.

sathishkumar_ramakrishnan · ‎2024-12-11

Hello Archer,

I have tested this MMEB values of the P3 relay with the TMW 101master [ Simulator tool], isolating T300 device. The phase voltage values are displayed negatively. Attached screen shot of the same.The Easergy pro will show the correct value, since its not the standard protocol implementation tool. As i mentioned earlier MMEB datatype is 16 bit value only. Hence its showing negative values once it crosses the range.

From P3 relay using the scaling factor need to provide the 16 bit data to T300 or any IEC101 master device integration for correct data representation. Not able to find information regarding scaling factor for P3 relay.