5 All About FCD 300
5.1 Brake Resistors
5.1.1 Dynamic Braking
With the FCD 300 the dynamic braking quality in an application can be improved in two ways, either with the aid of brake resistors or AC braking.
Danfoss offers a complete range of brake resistors for all FCD 300 frequency converters.
It is the job of the
brake resistor
to apply a load to the intermediate circuit during braking, thereby ensuring that the brake power can be absorbed by
the brake resistor.
Without a brake resistor, the intermediate circuit voltage of the frequency converter would go on rising, until cutting out for protection. The advantage
of using a brake resistor is that you can brake quickly with large loads, e.g. on a conveyor belt.
Danfoss has chosen a solution in which the brake resistor is not integrated into the frequency converter. This gives the user the following advantages:
-
The resistor's cycle time can be selected as required.
-
The heat generated during braking can be diverted outside the panel cabinet, where the energy can possibly be utilised.
-
No overheating of the electronic components, even if the brake resistor is overloaded.
An internal brake resistorcan be mounted on the small brake duty cycles.
AC braking
is an integrated function that is used for applications in which there is a need for limited dynamic braking. The AC braking function makes it
possible to reduce the brake power in the motor instead of in a brake resistor. The function is intended for applications where the required braking torque
is less than 50% of rated torque. AC braking is selected in par. 400
Brake function
.
NB!
The AC brake cannot be used if the required braking torque is more than 50% of rated braking torque. In such instances a brake
resistor must be used.
5.1.2 Brake Setup
The figure shows a brake Setup with a frequency converter.
In the following paragraphs, expressions and acronyms are used about
brake Setups that can be seen from the figure.
VLT
®
Decentral FCD 300 Design Guide
5 All About FCD 300
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