I work for a utility in Australia. SEL is now one of the leaders here. It was probably the mid 90's when they started gaining acceptance.
I would think that they got their start because their distance relays were significantly cheaper than the established companies - and they backed it up with...
This is also relay specific, but usually the inst o/c is fourier filtered to the fundamental (this also needs at least a cycle to evaluate).
Some relays give you the peak as an option if you want, it gives a faster time, but DC is then included
For a YDAC connection, inject A Phase-N on the Y side, and Aph to Bph on the DAC side.
Aph on the Y side is 0 deg, the A Ph on the DAC side is 180 deg (meaning Bph is also 0 deg)
Inject TAP1×1.732 on the Y side, inject TAP2 on DAC side - it will give you zero differential current, with...
Do a Phase-N injection on the Y side, with a Ph-Ph injection on the D side (do the current distribution to work out the correct phases to use)
The current injected on the Y side is divided by the TAP setting × SQRT(3)
The current on the D side is divided by TAP only.
Note that it operates two...
Yes an SR745 is a numerical relay.
If the application was for accurate metering (say for billing purposes) then an SR745 (or any other relay) and a P Class CT is not suitable in our organisation.
However they are OK for indications of Amps/Volts/Power etc to SCADA, and we use these relays and...
AS-C388 is roughly the same as AS1675, the main difference as is AS-C388 is in imperial units, AS1675 is metric.
I think I can follow your question, you are looking for accuracy up to the rated current. Accuracy Limit Factor is only relevant for fault currents.
I don't have a copy of C388, but...
What standard is the CT made to ?
In the Australian standard AS1675, this CT would have a 2.5 % error, when the CT is driving 20× Nominal current (F20 is the accuracy limit factor in AS1675) by producing 30 Volts at the secondary terminals.
In the IEC standard, this would be 4.335VA 2.5P20...
I think a plug setting of 1 means 1% of In, so what you have is 1.5×1% = 1.5% of In.
If In = 1 Amp, the pickup is 0.015 Amps secondary, which is 1 Amp primary with that CT Ratio.
Not sure what standard uses H1,X1 etc, but I assume it is similar to IEC60044 where P1 has the same polarity to S1.
This is something you cannot change (ie you cannot have P1 and S2 with the same polarity).
However it doesn't matter which way P1 or P2 points.
This statement is normally...
Engineers & manufacturers often get the numbers mixed up - I never rely on these numbers. Have seen costly mistakes made, and many unneccessary arguments because of this numbering system.
Get the person who mentioned the numbers to clarify the application - asking others to interpret what...
At our organisation, if we removed BF protection our clearance times would be too long, so we need it.
The risks are false trips by technicians, and bigger outages as well.
Our solution is to include BF Trip isolations in the formal switching instructions, along with formal training and...
Attachis a a drawing of what I believe is happening.
With the shorts applied, there are a number of paths for the current to flow, but it will all end up going back through the IB element.
If is 67 Amps in A and C, the remaining 166 Amps is going through IN
Without the shorts all seconardy...
When you inject with this connection, the current has a few different options, once it leaves the Bph CT secondary winding.
Go through the shorts, then back through the A & C phase elements, or go up through the IN element.
They will then summate and go back up through IB and back to the B...
Oscillography from SR relays is a CSV file rather than comtrade.
GE used to have a program called GE-Trade that allowed you to convert the files to comtrade, but it no longer works on the modern version of these relays.
They have suggested I need to buy Viewpoint Engineer - this is a fairly...
Theoretically speaking, a 3 phase fault and a 3 phase to ground fault are the same thing.
The software we use to calculate fault levels only gives us the 3ph-G option, however when the calcs are run there is no ground fault current.
There is only positive sequence components throughout the...
It sounds fairly similar to my role too.
My advice (for what it is worth) is to know what is important and make sure the proposed logic fulfils this requirement.
Test the settings yourself if you have access to the necessary equipment.
I have a view that it doesn't matter what your position is...
I think the MPB is what a lot of people call a "mouth organ".
It is for CDG and other electromechanical relays that use the same case.
They slot in between the sliding terminals at the bottom of the relay.
They are expensive, but if you are going to be testing older relays it is a worthwile...
