Installation
11
15
3.5 Regenerative Resistor Connections
An external regenerative resistor can be connected to the 7 position terminal strip connection points marked
external regen, . Refer to Figure 3.2. See the following example to determine if an external regenerative
resistor is required.
For determining if the internal regenerative resistor is sufficient use the following formula:
J
rotor
= Inertia of the rotor in lb-in-sec
2
J
load
= Inertia of the load in lb-in-sec
2
P = Power of regen resistor in watts
N = Speed of the motor in RPM
T
frict
= Frictional torque in lb-in
t
decel
= Deceleration time
t
cyc
= Cycle time
E = energy in motor in joules
where: P = Power of the internal resistor = 50 W
The internal resistor is sufficient if the calculated energy is
≤
200 Joules and the cycle time is greater than
the calculated cycle time.
Example:
J
rotor
=.0026 lb in sec
2
J
load
= 0.130 lb in sec
2
P = 50 W
N = 4000
T
frict
= 5 lb. in.
t
decel
= .25 sec
Since the energy is less than 200 joules and if the cycle time is greater than 1.9 seconds no external regen
is required. If the energy is greater than 200 joules or the cycle time is less than the calculated cycle time
consult the factory for the proper external regen resistor.
E= * (J
rotor
+ J
load
) * N
2
- * T
frict
* N * t
decel
t
cyc
=
1
1 6 1 6
1
8 5
E
P
E= * (.0026 + . 0 1 3 0 ) * (4000)
2
- * 5 * 4 0 0 0 * . 2 5 = 9 5 . 6 3
t
cyc
> > 1 . 9
1
1 6 1 6
1
8 5
9 5 . 6 3
5 0
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