Search results for query: *

Thank you kindly for your feeback. This particular setup is for a 600V system. The main generator breaker and ATS breakers are 600V 1200A 100% And come with electronic trip units with adjustable long time, short time, and instantaneous settings. The dry type transformers have thermal magnetic...

We are currently inplementing a design with a backup diesel generator which is used to backup critical loads in a facility. The generator is a CAT C32 PMG 1MW Standby, 1.25MVA. The generator is coupled to a traditional ATS with open transition transfer. When utility power is lost, the ATS will...

wbd, thank you kindly for your insight on this subject. I managed to find the equivalent verbiage to NFPA 70E-2015, Table 130.7 (C)(15)(A)(a) in the Canadian CSA Z462 which is derived from NFPA 70E. The CSA document states the two methods, (1) Incident Energy Analysis, (2) Arc Flash PPE Category...

The end user has the perception that the main breaker on the MCC can be set to maintenance mode when the downstream feeder breakers on the MCC is being operated. Their take on it is that they should be able to set the main breaker to maintenance mode while energizing feeder breakers on the MCC...

Wbd, yes an arc flash study has been done and the incident energies have been calculated. There is room to increase the pickup level during maintenance mode and still be within acceptable incident energy values.

Hello, I had a question with regards to utilizing the arc flash mitigation maintenance mode switch on a low voltage circuit breaker. Should the maintenance mode setting take into consideration the energization of a large load downstream? For example, the MCC main breaker has the maintenance...

Thank you David for your comments on this subject. I see your point. We will be running a 6 conductor cable for this. We will end up having to add additional terminals on the MCC end as the vendor has configured the field connection as a 4-wire.

Hi there We have several 4000v 3000HP motors which are fed from a Siemens MCC FVNR cells. My understanding is that medium voltage equipment is suitable for 90degC terminations where the ampacity of the conductor can be based on 90deg ampacities. How about the motor end? These are API 541 motors...

Thanks for your post David. Is this mainly because this is a differential application where you wouldn't necessarily see a balanced output if there was an internal fault on the motor? Why is it in Switchgear's that the neutral on the phase ct's are commoned up together and grounded? Wouldn't...

Hello all, We have a few medium voltage motors with a 50:5 core balance current transformer for each phase. Are there any issues with connecting the neutral of each CT together at the motor end so that you only run 4-wires back to the relay, where the fourth wire is the common neutral wire? Are...

Thank you kindly for your response. I managed to get the crouse hinds ballast data and their dropout voltage is 80%. So should be safe.

Hi Folks, I am carrying out a motor starting study. I have a 3100HP 4000V motor being started across the line at a system voltage of 4160V. Motornis a centrifugal with closed valve start. The main transformer is a 12MVA transformer. The voltage dip is 13% for 1.5s. This dip is also seen on the...

Thank you kindly for your response! Much appreciated!

Anyone?

Hello All, We have a several 4kV motors, horsepower range is anywhere from 2000HP to 3500HP. These motors come with 50:5 self balancing differential CT. The accuracy class of these CT's is C10. The worst case distance of the motor from the Multilin 469 Motor Protection Relay is 180 meters. I am...

Thank you all for your response. What I meant was overcurrent protection. But either way the secondary protection would trip on overcurrent. Looks like this is fine.

Thanks for your response Waross. I take it then this type of setup is acceptable?

Hi All, I have run into an existing installation where a 4.16kV Fused Contactor (360A) with 100E fuses feeds a 500kVA 4.16kV/480V transformer. There is a zero sequence CT and ground fault relay for the feeder which trips the contactor but there isn't any overload relay nor phase CT's. This is...

Hi Everyone, I have been trying to determine the proper ampacity derating for TECK Single Conductor cables when arranged in a trefoil arrangement in Cable Tray with 2x the cable diameter spacing between in each trefoil. I cannot seem to apply the 12-2210 rules. Out of all the rules in Rule...

Hello All, When implementing a differential protection for a transformer is there a problem if the accuracy class for the transformer primary CT is class C400 and the secondary CT at the switchgear is C200?