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voltage drop analysis

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PoliPoliCarps

Electrical
Nov 9, 2018
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SG
hello, can I ask I am conducting a voltage drop analysis with two medium voltage motors.
now my MTR1 is 94.53% voltage drop and the other one is 98.83% can someone please explain that being said why there's such difference
voltagedrop_analysis_fb5huy.png
 
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Look for a typo in your data entry.
What you show is equal for both motors, but there is a section with no sizing or lengths given.
That seems a strange arrangement with twin 46.4 Amp taps to feed each motor.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!
 
98.83% is the voltage at the switchgear bus and if it is same at the MTR2 also, there is something wrong in modelling the cables etc. between the switchgear and the MTR2?? This is my observation from the diagram. I would like to know your findings.
 
If the transformer short-circuit impedance is 4.45% then the voltage on busbar of 3.3 kV Switchgear it is 3261 V[98.83% of 3300].In my opinion the distance between main switchgear and secondary [close to motor cable terminal ] is negligible then both voltage at motor cables input has to be 98.83%.
According to IEC 60076-5 the minimum short-circuit impedance has to be 6%[+/-7.5%] -5.55% minimum minimorum.
If the short circuit transformer impedance will be 10% and the cable5 length will be 710 m [instead of 60 m] the voltage at motor Mtr1 terminals will be 3210 V [94.53%].
I don’t see another possibility.
 
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