Brake Resistor Selection - Danfoss VLT AQUA Drive FC 202 Design Manual

Type code and Selection

6.2.4 Brake Resistor Selection

When the speed reference of an adjustable frequency drive
is reduced, the motor acts as a generator and the
adjustable frequency drive brakes. When a motor acts as a
generator, it supplies energy to the adjustable frequency
drive which is collected in the DC link. The function of the
brake resistor is to provide a load on the DC link during
braking, thereby ensuring that the braking energy is
absorbed by the brake resistor.
If a brake resistor is not used, the DC link voltage of the
adjustable frequency drive continues to increase until it
6 6
disconnects for protection. The advantage of using a brake
resistor is that it enables braking of a heavy load quickly,
e.g., on a conveyor belt.
The brake resistors in this series are all external
components. Therefore, the brake resistor does not form
an integral part of the adjustable frequency drive.
The external brake resistor provides the following
advantages:
•
The resistor time cycle can be selected as
required.
•
The heat developed during braking can be
conveyed beyond the panel cabinet to allow the
energy to be used.
•
The electronic components do not overheat, even
when the brake resistor is overloaded.
126
®
VLT AQUA Drive FC 202
Recommended brake resistors are listed in
chapter 6.2.5 Recommended Brake Resistors and
chapter 6.2.6 Alternative Brake Resistors, T2 and T4. For more
information, see the VLT
Guide.
Horizontal and Vertical Loads
The Danfoss brake resistor range consists of two groups:
•
•
Figure 6.2 Horizontal Loads
100%
Figure 6.3 Vertical Loads
The brake resistor range is intended to cover the general
braking requirements for horizontal and vertical brake
applications.
To cater for both the horizontal and vertical ranges, three
types of brake resistors are available:
•
•
•
See chapter 6.2.5 Recommended Brake Resistors and
chapter 6.2.6 Alternative Brake Resistors, T2 and T4 for
ordering information.
Danfoss A/S © 09/2014 All rights reserved.
®
Brake Resistor MCE 101 Design
Brake resistors for horizontal loads (conveyors,
trolleys, gantry cranes, etc.), see Figure 6.2;
Brake resistors for vertical loads (cranes, hoists,
elevators), see Figure 6.3.
150/160%
Aluminum-housed flat pack brake resistors
Aluminum-housed compact brake resistors
Steel grid brake resistors
150/160%
MG20N622