I took a picture of the bus structure showing the external CTs. The housing is aluminum and CTs are encapsulated. Grey epoxy ? Phase-C is most accessible and my issue is phase-C. I will revisit in in 2 days, but I have some breaker timing to do first in another GIS switchgear, they are at 34.5...
Stevenal:
This CT is from GIS gear, isophase and CT is external. Cannot imagine another primary path.
dtr2011:
No grounds on sec windings, all 5 leads are isolated, voltage drop test per tap as per ratios of winding.
would a 20A sat demag this unit? We have tried up to 12.5A to no avail.
Hi all:
Would appreciate some comments.
Tested a CT which does work when performing primary injection at 100 amps with some errors, so it does perform transformation. However I cannot obtain a typical X1-X5 saturation curve, and ratio testing is off of nameplate values. These are C200 rating...
Protection Class CTs are much easier to test than high accuracy clasd revenue metering CTs.
I like specialized automated test set much better than old school method. You still need your old school basic theory.
When it comes time to do pre-commissioning work which may total more than 500...
Power is calculated as per 3phase formula.
VT x CT x PTR x CTR x root 3 x cos theta.
remember that CT and VT are variables set in the System Sensing page.
Undervoltage is per unit of VT, so just becomes a number. Just have to check if the 27 element operates in a phase-to-phase or...
The difference will be the head pressure of the oil.
You can have negative pressure at the top but still have positive pressure at the bottom.
All the side mounted pressure gauges that I have seen on sealed transformers are installed near the top, in the gas space.
You can actually take an...
Two dominant make of NGR fault protection systems in Alberta are I-gard and Littlefuse-Startco. Their web sites are full of technical information. You may have to register.
The NGRs can be supplied from both of these companies but PowerOhm also makes power resistors for NGR uses.
Neutral...
@ kashali:
63x1 and 63x2 are the seal unit output contacts. The RPRR input contacts (3-wires) wiring to the seal-in unit is better connected for security when employing all 3 wires versus just 2 out of the 3.
The seal-in real control board has a security circuit if wired to both "a" and "b" contacts and operates more securely than using the "a" contact alone. This then would require the transitions of both contacts before issuing a trip output.
Check if both contacts from the RPRR are use versus a...
I guess there is never a good excuse from doing a proper commissioning job.
Have these failed breakers and the switchgear gone through the required AC dielectric tests ?
There should be a dielectric test voltage level for a 1 minute or 10 sec test recommended by the manufacturers of both the...
Yes we have standard phase CTs and zero seq CT at the contactor end for the applicable motor curves with feeder 50/51 protection. Motor is 1000 feet away.
Fault current in my estimation is greater that 2.7 x FLA or about 1030 amps. We are asking the vendor to confirm and our e-tap PN department...
Motor Data: 3500 HP SCIM, 95% efficiency, 4160V, Xd" = .18 or 1.133 ohm on 6.29 ohm base. Full voltage start cct.
CT Data: I have three zero seq CTs at the motor in standard differential config; T1-T4, T2-T5, T3-T6. It is a C50, ratio 100:5A.
My CT loop resistance measured at 2.3 ohms and CT...
Load break switch are design with a closing closing unto fault duty. Any fault on the system will be interrupted and cleared by the fuse.
Most arc flash are mainly attributed to human error. I would have no reservation in operating the manual handle with or without a bomb suit. The gear are...
Powercon makes a load-break disconnect which can be armed by putting the manual operating lever to the open position without the load-break switch openning. The arming process,charges the operating spring but a slotted mechanical blocking rod prevents the switch operating arm from moving over...
Since it is the capacitive current flowing through the inductive elements that produces the voltage rise, adding series reactance will increase the voltage rise and add more operational losses.
Too much capacitive charging current on 230kv lines and higher are normally mitigated by shunt...
