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Thank you. I measured the SF6 purity in our switchgear compartment (15 years old) using RH SF6 Analyzer 973, some are as low as 95%. Does this means we need to replace the gas? What is the minimum SF6 purity requirement for 66kV GIS switchgear?

hi, I am working on 66kV switchgear maintenance. I like to know what is the minimum requirement for the SF6 purity (% volume). I cannot find it on the manual, it only give dew point requirement like -5 degree C for switchgear and -10 degree C for circuit breaker. Thank you.

It is our main 11kV distribution substation which feed other remote secondary 11kV substations that are in interconnected ring network configuration.

We have 3 66/11 kV system transformers (18.8/27MVA) connected in parallel. Each transformer 11kV side have tap changer to keep the voltage at 11kV. I am wondering why some of automatic voltage regulator (MK 30) failed (indicated on it display screen), hence no automatic voltage regulation if the...

Hi, I/z is equal to current for this case because the Z is in percentage. Transformer rated current divided by Z (percentage impedance) is the available fault current of the transformer at the HV voltage if the Z impedance reference voltage is HV.

Thank you Ralph. Actually, I need the trip curve to do protection coordination. I will try Alstom again. Do you happen to know Square D MCCB? I do not know what trip curve to use for Square D MCCB type SMAF 31000. I can only find the trip curve for the MA type and cannot find SMA type in the...

Hi, I have this relay at site which may be more than 15 years old. The relay type is CDG31EG2012JD5. This relay is 3 poles Standard Inverse curve from the number 31 but is it 1.3s/10x curve, 3s/10x curve or other? Thank you.

Hi, Anyone have trip curve for Mitsubishi Electric No-Fuse Breaker NFE 800-s and Merlin Gerin Selpact In=1600A with protection type DN2 characteristic? I have try on the internet but cannot find. I suppose it is very old type. Thank you.

Hi, I have NZM12-1000 MCCB at site which I do not know much about. How to know the setting for overload time Tr is ON or OFF? This is a thermomagnetics type. Thank you.

ScottyUK, Thank you very much. You are great. Regards, Ahhie

Dear all, Where can I find the time/current characteristics for the 800A type J fuse used in Merlin Gerin LV SAIF feeder pillar (Type 1601). I have try the fuse manufacturer site - Lawson Fuses but did not find one. Hope someone can help me on this? Thank you.

Hi, A new 3 phase 110V VT circuit with earthed neutral, the cables and instruments connected to it have been meggered and found to be earth-free. Why 48V is measured when voltmeter is applied across the top and bottom of each of the three fuse holders? The three core cable is about 250m long. Is...