Based upon these considerations, the table below gives the
highest allowable rated secondary voltage when using a line with
+10% voltage tolerance:
Transformer VA
Rating
Maximum Rated
Secondary Voltage
1 - 100
44.7 Vac
100 - 350
45.5 Vac
> 500
46.8 Vac
Current Rating
The average current load of the 6415 is a function of the motor
used as well as motor speed and torque. To optimize the power
supply design, the supply current can be measured using a DC
current meter when the motor is producing the highest shaft
power. If it is difficult to make this measurement, assume the
maximum average load current equals the selected phase current.
Thus, if the DIP switch is set for 5 Amps RMS, assume the
maximum average power supply current is 5 amps.
The average transformer secondary current equals the sum of the
average currents for all 6415s powered by the supply. Because
the transformer supplies pulses of current to charge the “bus”
capacitor(s) on the other side of the diode bridge, the rms current
is higher than the average current. The transformer should have a
rated secondary rms current of at least 1.8 times the average
current.
Example
The transformer used to supply three 6415 drive modules, each
set for 5 Amps rms should have a rated secondary rms current of
1.8 * (5 + 5 + 5) = 27 amps or greater.
Note:
It is generally not advisable to significantly oversize the
transformer because this will increase rectifier surge current
during turn on, as well as capacitor ripple current.
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6415 Installation & Hardware Reference Manual - Rev E
