Etap Support, please: parameters to model MCC as basic loads

[VaGoJr]

Good morning,

Hope someone can shed some light on my case.

I need to model a big Motor Control Center (MCC) panel with a lot of Normal Feeders, DOL-motors, SS-Motors and VFD-Motors. Many of them not running at full load (less than 100%) and many of them affected by a Simultaneity Factor. This is a common scenario in a MCC.
This MCC is not designed by me, is from others so I am only interested in the information at the connecting point of the incoming and to define the ShortCircuit of the MCC busbar.

Having said that, I need to model in ETAP this MCC as basic as possible but valid for Short Circuit simulation and Load Flow analisys.
My idea is to model it as 4 sum loads fed from same busbar:
1) Feeder as Static Load; sum of demanded power for feeders
2) DOL-Motors as Induction Machine; sum of demanded power of DOL motors
3) SS-Motors as Induction Machine with "Voltage Control" type in "Start Dev"; sum of demanded power of SS motors
4) VFD-Motors as a VFD+LumpedLoad

I am concerned about that the results could not be valid, i.e. X-values and SC contribution.

Appreciated a lot if someone could support me, please.
Thank you in advance
Vagojr

[surgeArrester]

So, you are modelling a system in etap to have a valid short circuit and load flow, however, you are afraid that the results are not valid? Then, you're system is not valid in the first place..

This query is very vague. You should have valid model so that your results are valid.


Sent from Mars

[VaGoJr]

So, you are modelling a system in etap to have a valid short circuit and load flow, however, you are afraid that the results are not valid? Then, you're system is not valid in the first place..

This query is very vague. You should have valid model so that your results are valid.


Sent from Mars

You are totally right, sorry. Being honest I don't know how to model a MCC in ETAP, so my question would be:

*) How could I model a MCC (with a lot of feeder, DOL motor, SS motor and VFD motor loads) without modeling each load one by one?
*) Could it be such simple as to sum each load type regardless the individual X-values?
*) Would it be a good approximation for SC and LoadFlow? Please check the png attached.

Thank you a lot for your time and in advance looking forward to receiving your kind support in this matter
Regards

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[himmelstern]

this is very basic in etap

you need to put a bus, and this bus in properties, you select as mcc.
every load at this is a motor, and in every motor, you select the motor starting method. only the vfd is not at the properties, and you have to call the vfd from the items pannel.

with this you can make load flow, short circuit and motor starting method

may be with the one line diagram could be more clear.

[VaGoJr]

this is very basic in etap

you need to put a bus, and this bus in properties, you select as mcc.
every load at this is a motor, and in every motor, you select the motor starting method. only the vfd is not at the properties, and you have to call the vfd from the items pannel.

with this you can make load flow, short circuit and motor starting method

may be with the one line diagram could be more clear.

According to your indications, I understand that it is neecessary to model each motor one by one.
I have almos 50 motors and only need to model the effect at the incoming.
Thank you very much for your quick answer,

[himmelstern]

yes, or you can use lumped loads to group loads, or use a composite network to have a composite network to don't have a big one line diagram

[VaGoJr]

yes, or you can use lumped loads to group loads, or use a composite network to have a composite network to don't have a big one line diagram

ok, good, if you dont mind I have a last question in regards to the own results of the SC and LF calculations.

Do you know if it would be a good approximation for these calcs;
1) if I use a lumped load as a sum of the demanded power of all the motors?
2) or is better to use the installed power and include the percentage in the properties of the lump load.
3) if I use only one lumped load (sum of all the VFD motors) fed from one VFD box? the vfd box would be only one with higher value

appreaciated a lot your support and very useful for me
regards

[himmelstern]

I'ts prefered to use a composite network and inside on it put the mcc with your 50 loads. the study is better, you can simplify it with lumped load, but ......

for example you can resume a big concentration of loads in a power system, for example in a distribution power system using a lumped load, ie: a factory or a building, and not model it pice by pice, but calculations are more exact with the particular modelation.

for your study of the mcc you must model it, and do a motor start study, to know the voltage drop on the mcc busbar and feeder. for that you must specify every motor starting method configuration and motor.

I recomend you to see this video tutorial on etap, is basic, but very userful.

use the play list link
**** - >

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[surgeArrester]

By the way, what is modelation?


Sent from Mars