Advertisement
Spindle Amplifier Shunt Load
Regenerative energy during deceleration causes the normal voltage on the amplifiers bus to
increase. The amount of energy is application dependent and relates to total inertia. The
deceleration rate of the load determines the rate that voltage rises in the bus capacitors. The
MPA-50-306 is equipped with interconnections for an external shunt load. The shunt load is
an EXS-50-230.
The voltage on the bus is sensed and when it becomes too high a solid state device turns on
and causes a load to be placed in parallel with the bus. There are three protection devices
that are used to protect the amplifier from this application dependent loading. The shunt loads
are thermally protected to 85° C maximum, there is a fuse in series with the shunt load to limit
average power in the shunt, and if this fuse blows then another circuit measures the bus for an
even higher voltage and a high bus fault occurs and disables the amplifier.
For 230 volt amplifier products the shunt is turned on at 400 Vdc and turns off at 360 Vdc. A
hi bus fault occurs if the bus goes over 440 Vdc.
Model
Load
Fuse
Peak
Bus Cap
Continuous
ohms
amps
amps
MFD
Watts
(external)
MPA-50-306
8
MDL-7
50
12000
2000
In high inertia applications, energy stored in the load must be dissipated in the amplifier's
bridge, bus capacitance, and parallel shunt load.
The shunt load should be mounted external to the amplifier enclosure but within four feet of
the amplifier. The wiring can be accessed through a 3/4" seal tight connection with an optional
cover, or it can be wired directly.
25
Advertisement
