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Altivar
®
58 TRX AC Drives
Dynamic Braking Resistor Kits
© 2000–2003 Schneider Electric All Rights Reserved
34
09/2003
DYNAMIC BRAKING RESISTOR KITS
The dynamic braking resistor kit allows the ATV58 TRX drive controllers to function in quadrants 2 and
4 of the four quadrant speed/torque curve. In these quadrants of motor operation, the motor is
essentially a generator through which energy is transferred from the motor load back to the drive
controller. This results in elevated DC bus voltage to the drive controller which may cause it to shutdown
to protect itself. Dynamic braking resistor kits are commonly used to dissipate the excess energy
generated by the motor operating in this mode. The flow of current to the braking resistor is controlled
by the dynamic braking transistor (see the block diagrams on page 92–94).
The following table shows the minimum ohmic value of the resistor that can be used with the
ATV58 TRX drive controllers. Using lower than recommended values will cause excessive current flow,
exceeding the rating of the dynamic braking transistor.
The following charts show the motor braking torque capacity of an ATV58 TRX drive controller with a
braking resistor.
Characteristics of Braking Module and Resistors
Minimum Ohmic Value of Resistors
Which Can Be Used with ATV58 TRX Controllers
Model (ATV58) Minimum Resistance Value in Ohms Model (ATV58) Minimum Resistance Value in Ohms
U09M2
U18M2
75
U18N4
U29N4
U41N4
U54N4
85
U29M2
U41M2
38 U72N4 57
U54M2 31 U90N4 47
U72M2 25 D12N4 53
U72M2
D12M2
13
D16N4
D23N4
19
D16M2X 8 D28N4, D28N4X
D33N4, D33N4X
D46N4, D46N4X
14
D23M2X 8
D28M2X 4 D54N4, D54N4X 8
D33M2X 2.67
D64N4, D64N4X
D79N4, D79N4X
5
D46M2X 2.67
Braking Torque with Resistor
Constant-Torque Applications Variable-Torque Applications
1. Continuous braking torque (driving load) load factor = 100%.
2. Maximum transient braking torque (for 60 s).
1. Continuous braking torque (driving load) load factor = 100%.
2. Maximum transient braking torque (for 60 s).
25/30 50/60 75/90 100/120
0
Speed (Hz)
0.25
0.50
0.75
1.00
1.25
1.50
1
2
1
HiTorqGraf.eps
%Torque
25/30 50/60 75/90 100/120
0
Speed (Hz)
0.25
0.50
0.75
1.00
1.25
1.20
1.50
1
2
1
LoTorqGraf.eps
%Torque