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Motor Starting Transient Simulator

Inrush current · Voltage dip · Speed ramp · DOL / Star-Delta / Soft Starter / VFD

Motor HP
50 HP
FLA (NEC 430)
65 A
Peak Inrush
423 A
Inrush / FLA
6.5×
Voltage Dip
0.9%
Motor kVA
54.0 kVA

Starting Method

Direct On-Line: full voltage, max torque, 6–8× FLA inrush. Simplest and cheapest.

Motor Parameters

Motor Size50 HP
System Voltage480 V
Source Impedance5%

NEC 430 Branch Circuit

Conductor Ampacity (×1.25)
NEC 430.22
81 A min
Overcurrent Protection (×2.5 max)
NEC 430.52
163 A max
Overload Relay (×1.15 SF)
NEC 430.32
75 A max
Disconnect (×1.15 min)
NEC 430.110
75 A min
Starting transient — Current & Speed vs Time
0s1s2s3s0A65A130A260A390AFLATime (seconds)Current (A)Speed (%)
Starting Current
Motor Speed
FLA (rated current)
Voltage Dip: 0.9% ✓ Acceptable
IEEE 519 / utility guidelines: ≤5% dip for frequent starts, ≤10% for occasional starts. Higher dips require coordination with utility or reduced-voltage starting.