Internal Brake Chopper; External Brake Chopper; Contactors, Dc Bus And Brake Circuit - ABB ACS800 Application Manual

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Internal brake chopper

• Only one internal brake chopper is allowed to be active.
• If an internal chopper is used, it must be in the biggest converter.
• The maximum braking power of the brake chopper or the inverter must not be
exceeded.
• A contactor must be used in the resistor circuit for protection against brake
chopper faults and against the overtemperature of the resistor.

External brake chopper

• An external brake chopper can be used but not at the same time with an internal
brake chopper.
• The external chopper must be installed close, < 5 m, to the biggest braking
converter.
• The external chopper can be selected according to the braking power demand.
For more information, see the appropriate drive Hardware Manual.
• A contactor must be used for protection against brake chopper faults.

Contactors, DC bus and brake circuit

If converters with different charging circuits are connected directly to the main
supply, the DC links must be connected together via contactors. See
With an external or an internal brake chopper a contactor must be used for
protection against brake chopper faults.
• Contactors must be capable of cutting off the DC current. The maximum
operational voltage over the contactor is the DC voltage during the braking, i.e.
1.21 · 1.35 · U
• DC current rating for the DC contactor can be calculated by using equation 4.
I
DC
P
DC
U
DC
P
cont.max
voltage of the converter.
Design
1.
P
DC
---------- -
=
U
DC
≈
P
cont.max
⋅
= 1.35 U
1
is the drive power rating of the biggest converter and U
Table 1.
(equation 4)
is the supply
1