Installation manual

Danaher Motion Kollmorgen Appendix D
SERVOSTAR
®
S and SERVOSTAR
®
CD Series 125
DETERMINING RESISTANCE VALUE
The maximum allowable resistance of the regen resistor is that value which will
hold the BUS under its maximum value when the regen circuit is initially
switched on. For an AC servo system, the maximum allowable regen resistance
is given by:
EQUATION 3
R
MAX
=
V
V I
2
M
B M
3
Where: V
M
= maximum BUS voltage
V
B
= motor back EMF less motor losses
EQUATION 4
V
B
=
K N - 3 I (R
B M M
/ )2
Where: K
B
= back EMF constant (V (L-L) /KRPM)
N = motor speed prior to decel (KRPM)
I
M
=
deceleration current in motor (A
RMS
/ phase)
R
M
= motor resistance (ÙL-L)
I
M
= deceleration current in motor (A
RMS
/ phase)
DETERMINING DISSIPATED POWER
The average wattage rating of the regen resistor is a function of energy to be
dissipated and the time between decelerations. This average wattage rating for a
single axis system is given by:
EQUATION 5
P
AV
=
E
M
2
M
2
HYS
cycle
- (1 / 2)C(V - V
t
)
Where: t
cycle
= time between decels + time to decel (sec)
V
HYS
=
hysteresis point of regen circuit