Verifying The Capacity Of The Braking Equipment; Custom Resistors - ABB ACS800 Hardware Manual

Verifying the capacity of the braking equipment

1. Calculate the maximum power (P
2. Ensure the following condition is met:
The P
(1 minute of braking, 9 minutes of rest). If the actual duty cycle does not correspond to the reference
cycle, the maximum allowed braking power P
P
braking cycles.
3. Check the resistors selection. The energy generated by the motor during a 400-
second period must not exceed the heat dissipation capacity E
If the E
resistors are connected in parallel, two in series. The E
times the value specified for the standard resistor.

Custom resistors

Resistors other than the standard resistors can be used provided that:
• the resistance is not lower than with the standard resistors
WARNING! Never use a brake resistor with a resistance below the value specified
for the particular drive / brake chopper / resistor combination. The drive and the
chopper are not able to handle the overcurrent caused by the low resistance.
• the resistance does not restrict the braking capacity needed, ie,
where
P
U
R
• the heat dissipation capacity (E
(see step 3 above).
P > P
brmax max
values specified in the technical data table above are for the reference braking cycle
brmax
is given for two additional braking cycles. See below for directions for calculating P
br
value is not sufficient, it is possible to use a four-resistor assembly in which two standard
R
2
U
DC
P
max <
R
maximum power generated by the motor during braking
max
voltage over the resistor during braking, for example,
DC
1.35 · 1.2 · 415 VDC (when supply voltage is 380 to 415 VAC),
1.35 · 1.2 · 500 VDC. (when supply voltage is 440 to 500 VAC) or
1.35 · 1.2 · 690 VDC (when supply voltage is 525 to 690 VAC).
resistor resistance (ohm)
) generated by the motor during braking.
max
must be used instead. In the technical data table,
br
value of the four-resistor assembly is four
R
) of the resistors is sufficient for the application
R
191
for other
br
.
R
Resistor braking