Symbol Explanation - Delta Electronics AC Motor Drive VFD-G User Manual

Symbol explanation

P : Motor shaft output for load (kW)
M
: Motor efficiency (normally, approx. 0.85)
η
ϕ
cos
: Motor power factor (normally, approx. 0.75)
V : Motor rated voltage(V)
M
I : Motor rated current(A), for commercial power
M
k : Correction factor calculated from current distortion factor (1.05 - 1.1, depending on
PWM method)
P
: Continuous motor capacity (kVA) P
C 1
: Starting current/rated current of motor
k
S
n
: Number of motors in parallel
T
n
: Number of simultaneously started motors
S
: Total inertia (GD
2
GD
T : Load torque
L
t
: Motor acceleration time
A
N : Motor speed
Revision July 2008, EG03, SW V1.06
Appendix C How to Select the Right AC Motor Drive|
C1
2
) calculated back to motor shaft (kg m
=KP /ηcos
MnT
2
)
C-3