Elmo SERVO AMPLIFIER DBP SERIES - Manual (Page 66)

65
DBP - Rev 6/93
6.3 Load inductance
The total load inductance must be sufficient to keep the current ripple
within the limits - 50% of the adjusted continuous current limit. The current
ripple (Ir) can be calculated by using the following equation:
0.5 x Vs
Ir = ---------- (A)
f x L
L - load inductance in mH.
Vs - Voltage of the DC supply in Volts.
f - Frequency in KHz.
If motor inductance does not exceed this value, 3 chokes should be added (to
each motor phase) summing together the required inductance
Lch = L - Lp
Lch - Choke inductance
Lp - Total inductance between two phases (in Y connection it is the sum of two
phases).
6.4 AC power supply
AC power supply can be at any voltage in the range defined within the
technical specifications. It must have the capability to deliver power to the
amplifier (including peak power), without significant voltage drops. Any
voltage below the minimum or above the maximum will disable the amplifier.
The recommended AC voltage are:
1.2 x VAC(min) < VAC < 0.9 x VAC(max)
Note - Single phase connection:
When using a single phase supply, voltage drop due to loading is expected.
The magnitude of the voltage drop depends on the load current, motor velocity,
stiffness of the power source and total bus capacitance. It is recommended not
to use single phase connection for output current higher than 20A.
For 3U size amplifiers it is recommended to add external capacitance as
follows:
For 135V units up to 1200
µ
F
For 270V units up to 600
µ
F