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– Who knows the REF stability procedure? Both the voltage injecting method And the current injecting method?
– When you create in the zone or out zone fault for REF stability there will always be a flow of current.
– Short Primary Bushing Phase R S T with secondary terminal shorted after CT. Then Inject One Phase Voltage, Then Current will flow through the Primary bushing and NHV. Inject current from low voltage side, in R phase and check for current (secondary current and display current in relay) at high voltage side.
Pl inject current outside the REF CT covering zones – relay should be stable (should not trip)

Reverse the R phase secondary terminals at TB(HV side) and take measurements ( display and secondary)
– What about lv side y,b phases? should be short or kept open?
– Open.
– Repeat for the Y and B phases. Then for R, Y B combined.
– Note that NGR must be shorted Or it would be burned.
– What if it’s a Delta star transformer?
– HV and LV CTs must-read values to short and reverse secondaries at TB.
– How to test REF on the Delta side if it’s available with an earthing transformer?
– I think this is the connection but I don’t know why we short ckt on the delta side two phases?
– Because a single phase-to-earth fault on the star side will get reflected as a phase-to-phase fault on the delta side?
– Is this shorting mandatory for star Transformers also?
– what if short all the primary phases?
– It’s only if we inject three phases, Current will also loop. we stability 3 phase then REF

– Creating the fault within zones – you can do this by closing Earth switches (outside the CT zones). Creating the virtual Earth fault through closing the earth switches (outside the REF CT zones).

DIGSI 4, DIGSI 5, ETAP, PSCAD, IEC61850, PCM600, Testing & commissioning, Generator protection


– Do anyone knows how to do the AVR auto mode test on ABB RET670. The issue is over current blocking feedback that need to be recorded through goose with Omicron kit?
– Anyone can share the ABB REJ601 relay password to edit setting parameters
– Can we set CT ratio 650/1 in ABB REJ601
– Is there any option for the TCS circuit at Siemens SIPROTEC5 BCU 6MD
– it is urgent if anyone has information please share it.

For joining our discussion groups:

– I found some mismatch between PCM and IED technical Key, Does anyone here know how to fix this?
– If you have the right connectivity package concerning the IED software version, then create the bay from scratch and collect. Normally it detects it automatically

– Does anyone have a Methodology for End to End Pilot wire differential protection for the cable? Please share Thanks in advance.
– You have to download it from the SEL website

– Can anyone tell me about the MIF II digital feeder relay GE Overload thermal relay setting detail of cooling time and heating time? model no GEK-106237Q

– Does anyone have Schneider electric relay SEPAM T82 RELAY technical catalog?
– You can download it from

– Which parameter (Measured or Derived) does the relay sense to trip the relay if the IN exceeds the setting? IN Measured or IN Derived?
– Check the Analog card whether a separate coil is provided for neutral.
Protection engineer user x: Which relay?
– It depends upon which factor you are using in settings.
– What is the issue? When I’m going to install PCM 600 v2.10 then this error will come.
– Which SQL Server is needed for PCM 600 v2.10?
– That’s telling 2014 express.

Protection engineer user x: Guys, If anyone has IEC 60870-5 – 101 & IEC 60870-5 – 104, then please send…
Protection user x: Is there any one user of the DEIF Controller?
Protection engineer user x: Anyone has an idea of IoS A & IREF N in ABB REF relays?
Protection engineer user x: IOS A & IREF N.
Protection user x:

– Why do we put an OLTC of the generator in local mode?
– Are you talking about the OLTC of Trs at Generation Station?
– Local it’s mean cannot access remotely, depending on operation requirements.

-We lost the password of the MicomP143 relay. Is there any option to reset the password?
– You need to contact customer care with security code device details

– Does anyone know how to Synchron the date and time of relay micom from the Serial Port?

For joining our discussion groups:


– What is the IEC standard for relay setting coordination, the minimum operating time between two relays i.e. source & load?
– 200msec.

Our 2 latest courses are on the website. You can see details here:
🔸generator protection 🔸testing &commisioning

For joining our discussion groups:

All Elec-Engg courses are available for you to take:


💠 IEC61850
💠 PCM 600
💠 Micom
💠 Testing & Commissioning

💠Generator protection


💠 Busbar protection


– What could be the possible cause of the increase in the current of one phase of a generator? My generator trips of overcurrent in Phase B. I have done all the checks on the generator and it seems okay.

– Is it possible to inject both 50Hz and 100Hz of two current sources in the CMC356 Kit?
– Yes, parallel sources 1 and 2 and use source 1 for 50Hz and source 2 for 100Hz.

– The above method should work for checking harmonic restraint blocking and tripping percentage. In my quick CMC, if I change 100hz then remaining all sources also will get changed into 100hz for harmonics.

– Right-click and select unsync.

– Can anyone explain the function of the three CTs on the neutral side?
– Possibly for generator differential protection. These CTs are connected on the main winding of Gen. However, on the neutral side of Gen and thus, referred to as neutral CT.
– I was thinking if done in residual connection then it will be used for stator earth fault protection on the neutral side. But the CTs are not residually connected.

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