Absolutely, as the other posters have said. The MCC is the structure for feeding local loads.
I have always fed lighting transformers, battery chargers, UPS bypass transformers etc. from 480V MCC's. Just put in a correctly sized molded case circuit breaker, size the cable properly and you're set.
We use capacitor banks when starting large (14000HP+) motors in order to keep system voltage above 80% nominal. Injecting VARS to the system could decrease the "sag" the PC is seeing when the motors are starting.
Thanks for the response zog, the other hurdle after deciding to use the clamp-on ground test is to make sure a thorough procedure is written/in place and the contractor understands how to properly conduct the test.
For thise interested, I just received an email from an AEMC Instruments...
I am using 311L's for primary line differential protection (POTT) for 230kV, 69kV and 13.8kV transmission as well as a 351S for backup diff. scheme (DCB).
For high speed transfer tripping, the 311L's with F.O. communications is the way to go.
Thanks, those are the same conclusions I have come to. I was hoping I had missed a white paper (other than the one I referenced, which is put out by the same company selling the meter) or IEEE reference as it would be much easier to sell to the client who does not like deviating from the spec...
Reference thread:
thread238-231298
Good morning all,
I wanted to get everyone's experience/opinion on using a clamp on meter instead of the traditional fall-of-potential test for ground testing. One of the general contractors is asking for a waiver to our current specs which state a...
I find its much easier to get a job done when the politics/formalities are reduced in the workplace. I have the luxury of working with a small group schoolmates and other friendly people on a multi billion dollar construction job. Things get stressful and arguments ensue at times, but we can...
frv (Structural) 16 Aug 10 13:35
In my line of work, it's not common for employers to pay for education not directly related to the industry.
You don't work for an EPC do you? ;)
Greg you are absolutely right. Even if management is not in your career plan, engineers can really learn alot from an MBA program. One example that comes to mind is being able to speak to Management, using their language, in order to get what you want. An engineer's job is to design equipment...
Batman,
I found that the NCEES practice exam book (I believe it has a distribution station on the front) is VERY similar to the actual test as far as types of questions and difficulty. It would be very beneficial if you could work all 80 problems in that test as well as be able to navigate the...
How about starting time? Anyone see an issue with a prolonged start? I'm thinking about protective devices tripping out to do starting current being applied longer than normal. (maybe not applicable on a 400V system...)
Shozza,
The relay isn't operating at 12-18 amps, the motor is drawing that much current. The capacitor is charged off the control voltage at the relay.
The three phase CT's are connected in a wye configuration with the residual current element (51N) on the neutral leg of this connection. It's not a calculation but more of a measurement and will pick up any phase current imbalance. I agree with JGHRIST that the imbalance most likely came from...
We also use maintenance switches on each switchgear lineup which arms the 50 Elements of the main relays before any work is done on the gear.
I highly recommend this solution opposed to not using an instantaneous element in situations where the inst. element interferes with downstream coordination.
