Planning the braking system
■
Verifying the load capacity of the braking equipment
1.
Calculate the maximum power generated by the motor during braking (
P
max
).
2.
Ensure that the maximum power rating of the braking equipment is equal to or greater
than
P
max
.
The
P
brmax
values specified in the ratings table are for the reference braking cycle
(1 minute of braking, 9 minutes of rest). If the actual duty cycle does not correspond to
the reference cycle, either use the power rating given for the other two reference cycles
(
P
br
), or calculate the maximum braking power for a custom braking cycle. See below
for instructions on calculating
P
br
for other braking cycles.
3.
Check the resistor selection. The energy generated by the motor during a 400-second
period must not exceed the heat dissipation capacity of the resistor (
E
R
). If you use
custom resistor(s), see also the separate instructions below.
If the
E
R
value of the resistor is not sufficient, it is possible to use a four-resistor assembly
in which two resistors are connected in parallel, two in series. The
E
R
value of the
four-resistor assembly is four times that of a single resistor.
Custom resistor
Resistors other than those available as D151 can be used provided that
•
the resistance is not lower than the value given in the ratings table
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 would not able to handle the overcurrent caused by the low resistance.
•
the resistance of the custom resistor does not restrict the braking capacity needed, ie.
P
max
<
U
DC
2
/R
where
Maximum power generated by the motor during braking
P
max
Voltage over the resistor during braking. UDC equals
U
DC
1.35 · 1.25 · 415 V DC (when supply voltage is 380 to 415 V AC)
1.35 · 1.25 · 500 V DC (when supply voltage is 440 to 500 V AC) or
1.35 · 1.25 · 690 V DC (when supply voltage is 525 to 690 V AC)
Resistor resistance (ohm)
R
•
the heat dissipation capacity
E
R
of the resistor is sufficient for the application (see step
3 above).
Calculating the maximum braking power for a custom duty cycle
These rules must be met during any braking cycle:
1.
Braking energy transferred during any ten minute period must be less than or equal to
the energy transferred during the reference braking cycle (1/9 min).
2.
The maximum braking power for a custom braking cycle (
P
br
) must not exceed the rated
maximum value
P
brmax
.
The rules as equations:
1.
n ×
P
br
×
t
br
≤
P
brmax
× 60 s =>
P
br
≤ (
P
brmax
× 60 s)/(n ×
t
br
)
206 Resistor braking
Summary of Contents for ACS880-07CLC
Page 1: ...ABB industrial drives Hardware manual ACS880 07CLC drives ...
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Page 91: ...PE PE 10 13 12 22 Electrical installation 91 ...
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Page 132: ...5 4 11 7 6 8 132 Maintenance ...
Page 133: ...14 15 16 12 13 17 Maintenance 133 ...
Page 141: ...5 Set the real time clock Maintenance 141 ...
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Page 176: ...ACS880 07CLC 0390A 7 C121 marine construction 176 Dimensions ...
Page 177: ...ACS880 07CLC 1310A 7 Dimensions 177 ...
Page 178: ...ACS880 07CLC 2180A 7 C121 marine construction 178 Dimensions ...
Page 179: ...ACS880 07CLC 3260A 7 C121 marine construction Dimensions 179 ...
Page 181: ... 2 D8D Dimensions 181 ...
Page 182: ... 3 D8D 182 Dimensions ...
Page 183: ... 4 D8D Dimensions 183 ...
Page 185: ...Inverter module cubicle with two R8i modules bottom cable exit Dimensions 185 ...
Page 186: ...Inverter module cubicle with three R8i modules bottom cable exit 186 Dimensions ...
Page 187: ...Brake chopper cubicle D150 Dimensions 187 ...
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