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Starting large motor 2MW with captive transformer using temporary transformer

Starting large motor 2MW with captive transformer using temporary transformer

Starting large motor 2MW with captive transformer using temporary transformer

(OP)
Dear all,

I need some advices regarding to start large motor cooling water pump 2000kw, 3.3kV(detail info is listed below) using captive transformer 3500kVA (13.8kV/3.3kV).
And IMHO, captive trafo is supplied from temporary transformer 3000kVA (20kV/3.45kV) which sufficient to deliver starting motor 2000kW (I think), but not bigger than the captive tranformer 3500kVA,
This captive trafo also through using backfeed transformer 10MVA, 3.3kV/13.3kV (normal is step down Dyn-11, 13.8kV/3.45kV) which I have proposed ground protection transformer or zig-zag trafo for delta side of the 10MVA trafo.
With this starting scheme, is it sufficient to make start of this motor?

Motor data:
Pump driven for motor cooling water: 2000kW,
BHP: 1760kw, spee: 600rpm, poles :10
LRC motor: 500%
PF motor at starting : 0.2
Voltage: 3300kV, 3phase, 50Hz
Full load amp: 458Amp
temp rise:B
Efficiency and pf: 95.5% and 80%at 100%

I have calculated that it can work with using captive trafo 3500kV with detail below:
Voltage: 13.8kV/3300kV
Amp: 146.43/612.34
short circuit impedance: 4
Vector group: Dyn-11

This motor should be normal operated using STG 19MVA,13.8kV
But within start up comm this captive trafo will be fed from backfed tranformer 10MVA,with detail data below:
Voltage: 3450V/13.8kV
Amp: 1673.48/418.37
short circuit impedance: 8%.
Vector group: Dyn-11

This trandformer is also energized from temp trafo 3000kVA, with detail below:
Voltage: 20000kV/3450kV
Amp: 86.6/502.04
short circuit impedance: 7%.
vector group: YNyn-6
The utility system is using 20kVA, with short circuit impedance 500MVA,

Do you have any experience this scheme, and other advices will be welcome.

Thank you,

Athan


RE: Starting large motor 2MW with captive transformer using temporary transformer

Wow, that's a LOT of transformers in series! Why?


"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington

RE: Starting large motor 2MW with captive transformer using temporary transformer

(OP)
yes,

I could not avoid this since this scenario happen when DEG is run out (2 fail), and when this start-up commissioning, this alternative is just only our option,

hope you can give us some advices,

Thx,

At

RE: Starting large motor 2MW with captive transformer using temporary transformer

IMHO the voltage drop will be more than 50% and I never heard an induction motor starting D.O.L. in this conditions.ponder

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