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Whenever the load applied to a motor attempts to overtake the
motor, the motor starts receiving power from the load instead of
providing power to it. It does this by acting as a generator. When
this happens it puts power back into the drive’s power supply
capacitors. This power is directed back into the motor as soon as it
is needed.
Under many applications, some power goes back into the drive with
each deceleration of the load. As long as this energy does not cause
the bus voltage to exceed a safe level, no other form of regeneration
is required.
In many horizontal applications where aggressive deceleration is
demanded, and in most vertical load applications, the bus voltage
would exceed safe levels. In these applications, switching circuitry
and a high wattage resistive load are employed to dissipate this
excess energy as heat.
All Tol-O-Matic Axiom® Plus units provide an internal regeneration
resistor. In addition, all Axiom Plus units provide for connection of a
high wattage external resistor pack to accommodate the most severe
applications.
Since the internal resistors of the Axiom Plus PV series can dissipate
the full peak load, no external resistor pack is required in most
applications. A simple rule of thumb is to use the internal resistor
for horizontal screw-drive actuator applications. Many belt-drive
and vertical screw-drive actuator applications can also use the
internal resistor if the duty cycle is low. For high duty cycle or heavy
vertical load applications, use an external regeneration resistor.
Caution!
If bus voltage regeneration causes a drive temperature
fault, an external regeneration resistor is needed.
Caution!
Either the internal or the external resistor pack should
always be connected on any Axiom PV series application. Never
connect both, as this may destroy the internal switching circuitry.
All Tol-O-Matic Axiom Plus units incorporate a brake relay. This is
designed for use with an “energize-to-release” type of load brake.
The brake relay contacts are rated for 3A. The relay contact is closed
(brake released) only when the drive is enabled and not faulted. At
any other time, the relay contacts open to apply the brake.
!
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10 -1
Regeneration Resistor Use & Sizing
10
