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I really appreciate your professional feedback. It appears that I made an error in saying synchronization of both sides using a coupled DC bus. Under normal operation, the DC outputs of the VFDs are interconnected through the contactor. In the event of a VFD failure, the operator will deactivate...

Thank you for your feedback! On a bucket wheel reclaimer, there are two Variable Frequency Drives (VFDs) for the long travel drive motors: one for the left side and another for the right side. The client wishes to synchronize both sides using a coupled DC bus while operating the machine...

Thank you very much for your reply. I considered the thermal OL contact of the resistor as a safety input to VFD.

Thank you very much your reply. I will go with 1000VDC contactor.

Hi, I have two VFD 45kW, 600V, 3Phase, 60Hz. The DC bus of two VFDs are required to connect trough a contactor. What is the voltage rating of the contactor I should consider? Will 690V rated contactor suitable for this? Your comments is much appreciated. Thanks, Kani

Hi, Do we need to protect the VFD braking resistor using fuses? If so how do I calculate the fuse rating? The braking resistor is 400W and 18Ohm, VFD output 600V, 3Phase, 60Hz. VFD rating is 45kW. I appreciate your feedback and help. Thanks, Kani

Thanks you for your valuable feedback.

Hi, Why we need to consider 1000V rated power cable for 600/347V Y system, solidly or resistance grounded. Your feed back is much appreciated. Tanks, Kani

Hi, Can I use 15HP 460V 60Hz motor on 480V 50Hz System? What are the formulas to calculate FLA of this motor at 480V 50Hz. Please provide a calculation example. Thanks, Kani

Thanks all! According to your replies and my search, I came to a conclusion System N+1: N is required units and +1 will be standby. If one of N fails, the standby unit will kick on. 75kVA Generator Example: 3x 25kVA online and one 25kVA is standby. or 40kVA+35kVA online and another 40kVA is...

What i think n+1 shall have all units same. as per jraef ( 4 x 25kW). N-1 can be any combination. If any unit fails, non of other units shall be overloaded. example: for 75kVA requirement, we can use 40+40+35 three gen set in parallel. I think this is what Crshears means above. any comments?

Thanks all for your replies. For Jraef: if we are using 4x25W, this is N+1. Isn't it?

Hi, Can you please help me to understand the different between N+1 and N-1 redundancy. If the actual requirement is 75kW heater. What will be the combination for N-1 and N+1 redundancy system Thanks

Thanks cuky2000!Much appreciate your reply.

Hi, Do wee need to use stress cones (Termination kit) for MV Tray cables 4.16kV and 23kV. Please share your knowledge and recommendation. thanks, Kani

Thank you cuky2000 and 7anoter4. I think we are in good shape with your replies. 7anoter4, your reference to Table 5 for P and Q. I checked BS7430, but i couldn't find the values. Please let me know more detail of the reference table. Thanks, Kani

Thanks Waross. It is a good article. I really want to find the calculation formula for the horizontal conductors encased in cement. Hope someone help me.

Hi!, I am looking for calculation formula for ground resistance of horizontal conductor encased in concrete. There is a formula in Ieee80-2000 for the vertical ground rod. Appreciate if some one help me. Thanks, Kani

Thank you very much! This is very nicely explain. Just Ohm low and short circuit calculation. I think I got the detail what I was looking for. Thanks once again!

Thanks! Is there any way to find the earth current %. I followed the IEEE 80-2000, but there was no formulas when the fault at the station. The soil is 2800 Ohm.m and they need 1 Ohm. It is impossible to achieve this with a grid unless they spend $$$ on coppers. Any experience with encased...