Motor starting calculation.xls
6
Main_Data document.xls MOTOR STARTING Client: Project: Motor: 800 hp Motor Case: Utility Supply & Base Data: Transformer: Utility Gen. Volts (UGV 25 kV Base MVA: 100 MVA Size: 1 MVA Base Pri. Volts: 25 kV Primary Volts 25 kV SCMVA: 36.3274 MVA at 25 kV Secondary Volts: 4160 V X/R Ratio: 1.4 p.u. Impedance: 6% Base Sec. Volts: 4160 V X/R Ratio: 10 p.u. Feeders: Motor: MCC Motor Conductor Size: 500 1 AWG/MCM Horsepower: 800 hp #/Phase: 1 1 Rated Voltage: 4160 V Length: 100 200 ft Full Load Curren 98.5 A Other Loads: Inrush Current: 750 %FLC Locked Rotor PF: 17 % Heating & Lighting Load 0 kVA 90 %PF Full Load PF: 88.5 % Capacitor on Starter Te 750 kVA 3300 V Cap. Correct. PF 92 % Capacitor on MCC Bus 60 kVA 4160 V Starting Torque: 140 %FLT Efficiency: 95 % Calculations: PF Capacitor: 49.9 kVA FV Inr 5322.94 kVA Horsepower: 800 hp p. Correct. PF: 83.15 % 738.75 A ll Load Current: 99 Amps Bases: 25 4160 4160 4160 FLT Motor Starting: Tap Prim. Sec. MCC Motor Torque Motor MCC % %Volts %Volts %Volts %Volts % A kVA Initial Load: Voltage 100.00 100.00 100.00 Across the Line: Voltage 92.31 74.28 74.22 73.96 71 546 2,247 Flicker 7.69 Auto-Transforme 80 Voltage 94.60 81.97 81.93 65.31 55 482 1,738 Flicker 5.40 Reactor: 65 Voltage 94.62 81.56 81.52 53.66 37 396 1,777 2.19 Ohms Flicker 5.38 5.80 mH Short-Circuit: Based on UGV Prim. Sec. MCC Motor Steady-state 25 kV Bus Bus Bus Bus RMS from utility MVA: 36.33 11.77 11.74 11.62 system only. Current (A): 838.9 1633 1629 1613 X/R: 1.40 3.74 3.72 3.45
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Motor starting calculation
Transcript of Motor starting calculation.xls
Main_Data
document.xls
MOTOR STARTING
Client:Project:
Motor: 800 hp MotorCase:
Utility Supply & Base Data: Transformer:Utility Gen. Volts (UGV): 25 kVBase MVA: 100 MVA Size: 1 MVABase Pri. Volts: 25 kV Primary Volts 25 kVSCMVA: 36.3274 MVA at 25 kV Secondary Volts: 4160 VX/R Ratio: 1.4 p.u. Impedance: 6 %Base Sec. Volts: 4160 V X/R Ratio: 10 p.u.
Feeders: Motor:MCC Motor
Conductor Size: 500 1 AWG/MCM Horsepower: 800 hp#/Phase: 1 1 Rated Voltage: 4160 VLength: 100 200 ft Full Load Current: 98.5 AOther Loads: Inrush Current: 750 %FLC
Locked Rotor PF: 17 %Heating & Lighting Loads: 0 kVA 90 %PF Full Load PF: 88.5 %Capacitor on Starter Term. 750 kVA 3300 V Cap. Correct. PF: 92 %Capacitor on MCC Bus 60 kVA 4160 V Starting Torque: 140 %FLT
Efficiency: 95 %Calculations:
PF Capacitor: 49.9 kVA FV Inrush: 5322.94 kVA Horsepower: 800 hpCap. Correct. PF: 83.15 % 738.75 A Full Load Current: 99 Amps
Bases: 25 4160 4160 4160 FLTMotor Starting: Tap Prim. Sec. MCC Motor Torque Motor MCC
% %Volts %Volts %Volts %Volts % A kVAInitial Load: Voltage 100.00 100.00 100.00
Across the Line: Voltage 92.31 74.28 74.22 73.96 71 546 2,247Flicker 7.69
Auto-Transformer: 80 Voltage 94.60 81.97 81.93 65.31 55 482 1,738Flicker 5.40
Reactor: 65 Voltage 94.62 81.56 81.52 53.66 37 396 1,7772.19 Ohms Flicker 5.385.80 mH
Short-Circuit: Based on UGV Prim. Sec. MCC MotorSteady-state 25 kV Bus Bus Bus BusRMS from utility MVA: 36.33 11.77 11.74 11.62system only. Current (A): 838.9 1633 1629 1613
X/R: 1.40 3.74 3.72 3.45
A23
This input represents constant impedance loads, but not motor loads. DO NOT include constant impedance loads to represent motor loads, else this will result in a lower than actual voltage flicker. Motor loads are constant power loads. These loads have not been included in this spread sheet. It has been found through calculations that the normal range of voltage flicker is the same both with and without constant power loads.
A24
Capacitor is connected to the starter motor terminals.
A25
Capacitor is connected to the MCC bus.
I31
Torque is based on a motor manufacturer's curve which considers iron saturation. This results in less motor torque than the classical: Torque = K * Motor Volts^2
A43
Assumes steady-state short-circuit RMS current contribution from the power utility company only.
Accel
document.xls Page 2
MOTOR ACCELERATION
Client:Project:
Motor: 800 hp MotorCase:
Input Data:
Synchronous Speed (SS): 3600 rpm
Full Load Torque (FLT): 1167 lb.ft.
Total Inertia (WK^2): 122 lb.ft^2
Motor Locked Rotor Torque: 150 %FLT
Motor Pull-up Torque (PUTQ): 140 %FLT
Motor Pull-up Torque Speed (max. 75%): 50 %SS
Motor Break-down Torque: 220 %FLT
Load Curve Exponent (0=level, 1=lin., 2=sq.): 0.1
Load Break-away Torque: 2 %FLT .
Load Rated Speed Torque: 51 %FLT
Auto-Transformer Start, at 80 % Tap.
Motor Load Motor Motor Motor MtrRV MtrRV MtrRV Time Pri.V MCC.V Accel.T
%Speed %FLT %FLT %FLA %PF %Volts %FLA %FLT Sec. %Volts %Volts %FLT
0 2.0 150.0 750 17.0 65.3 490 59.2 0.0 94.6 81.9 57.2
10 20.0 146.4 745 17.6 65.4 487 58.0 0.3 94.6 82.1 38.0
20 30.0 143.6 740 18.1 65.5 485 57.1 0.6 94.6 82.2 27.1
30 40.0 141.6 734 18.7 65.6 482 56.4 1.2 94.7 82.3 16.4
40 45.0 140.4 729 19.2 65.7 479 56.1 2.1 94.7 82.4 11.1
50 48.0 140.0 724 19.8 65.8 477 56.2 3.4 94.7 82.6 8.2
60 50.0 141.6 711 20.3 66.1 470 57.3 5.0 94.8 82.9 7.3
70 50.5 145.1 688 22.5 66.6 458 59.5 6.5 94.9 83.5 9.0
80 51.0 153.7 656 28.0 67.2 441 64.3 7.6 95.1 84.4 13.3
90 51.0 183.7 568 39.0 69.3 393 81.6 8.2 95.6 87.0 30.6
95 51.0 220.0 480 50.0 71.6 343 104.4 8.4 96.3 89.9 53.4
97.5 51.0 168.6 295 67.6 77.0 227 92.6 8.4 98.2 96.6 41.6
99 51.0 100.0 100 88.5 83.3 83 64.2 8.5 100.7 104.2 13.2
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0
0.0
50.0
100.0
150.0
200.0
250.0
MTRFVT
MtrRVT
Load T
Time (sec.)
To
rqu
e (
%F
LT
)
Accel
document.xls Page 3
#N/A
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0
0.0
20.0
40.0
60.0
80.0
100.0
120.0
Pri. V
MCC V
Motor V
Time (sec.)
% B
ase
Vo
lts
100 10000.1
1.0
10.0
Motor Amps (Log-Log)
Amps (%FLC)
Tim
e (
se
c.)
-->
Miscel.
Page 4
XLSTARMISCELLANEOUS CALCULATIONS
System Impedance and Short-Circuit MVA:
R1 = 1.6 per unit BMVA = 100 MVAX1 = 2.24 per unit SCMVA = 36.32739 MVA
BMVA = 100 MVA X/R Ratio= 1.4
SCMVA: 36.32739 MVA Z1: 2.752744 per unitX/R Ratio: 1.4 R1: 1.6 per unit
Z1: 2.752744 per unit X1: 2.24 per unit
Pre-start Voltage (%) 100New SCMVA: 36.327
Torque800 hp
3600 rpmTorque = hp x 5252 / rpm ft.lb.= 1167.1111 ft. lb.
