GE Industrial Solutions AF-650 GP General Purpose Drive - Manual (Page 29)

9.1.4 Optimum Braking
Dynamic braking is useful from max. speed down to a certain frequency. Below this frequency DC braking is to be applied as required. The most efficient way of
doing this is to use a combination of dynamic and DC braking. See illustration 11.1. The parameters can be found further on in this instruction in the chapter
Programming.
For further information about DC Braking see section 11.1.1.
Illustration 9.1:
NB!
When changing from dynamic to DC braking, there will be a short period (2-6 milliseconds) with very low braking torque.
How to calculate optimum DC-brake cut in frequency:
Slip S =
nO − nn
nO
× 100 %
Synchronous speed n0 =
f × 60
p
[1/min]
f = frequency
p = no. of pole pairs
n
n
= speed of the rotor
DC-brake cut in frequency = 2 × S × f
100
Hz
AF-650 GP Brake Resistor Design Guide
28
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