ABB ACS880-34, Руководство по оборудованию

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230 Resistor braking

Selecting custom resistors
If you use a resistor other than the default resistor, make sure that:
1. The resistance of the custom resistor is greater than or equal to the resistance of the
default resistor in section Brake resistors on page 233 :
where
2. The load capacity of the custom resistor is higher than the instantaneous maximum
power consumption of the resistor when it is connected to the drive intermediate DC
circuit by the chopper:
where

Selecting and routing external brake resistor cables
Use the same cable type for the resistor cabling as for the drive input cabling, or,
alternatively, a two conductor shielded cable with the same cross-sectional area.
Minimizing electromagnetic interference
Obey these rules in order to minimize electromagnetic interference caused by the rapid
current changes in the resistor cables:
•
Shield the braking power line completely, either by using shielded cable or a metallic
enclosure. Unshielded single-core cable can only be used if it is routed inside a
cabinet that efficiently suppresses the radiated emissions.
•
Install the cables away from other cable routes.
•
Avoid long parallel runs with other cables. The minimum parallel cabling separation
distance should be 0.3 meters (1 ft).
•
Cross the other cables at right angles.
•
Keep the cable as short as possible in order to minimize the radiated emissions and
stress on chopper IGBTs. The longer the cable the higher the radiated emissions,
inductive load and voltage peaks over the IGBT semiconductors of the brake chopper.
Maximum cable length
The maximum length of the resistor cable(s) is 10 m (33 ft).
R Resistance of the custom resistor
WARNING ! Never use a brake resistor with a resistance smaller than R
min
.
The drive and the chopper are not able to handle the overcurrent caused by
the small resistance.
R
min
Resistance of the default resistor
P
r
Load capacity of the custom resistor
U
DC
Drive intermediate DC circuit voltage.
1.35 · 1.2 · 415 V DC (when supply voltage is 380 to 415 V AC)
1.35 · 1.2 · 500 V DC (when supply voltage is 440 to 500 V AC) or
R Resistance of the custom resistor
R > R
min
P
r
>
U
DC
R
2