Definition For Brake Usage Ed% - Delta Electronics AC Motor Drive VFD-VE Series User Manual

Appendix B Accessories|
1. Please select the factory setting resistance value (Watt) and the duty-cycle value (ED%).
2. If damage to the drive or other equipment are due to the fact that the brake resistors and the
brake modules in use are not provided by Delta, the warranty will be void.
3. Take into consideration the safety of the environment when installing the brake resistors.
4. If the minimum resistance value is to be utilized, consult local dealers for the calculation of the
Watt figures.
5. Please select thermal relay trip contact to prevent resistor over load. Use the contact to switch
power off to the AC motor drive!
6. When using more than 2 brake units, equivalent resistor value of parallel brake unit can't be
less than the value in the column "Minimum Equivalent Resistor Value for Each AC Drive" (the
right-most column in the table). An example of 575V 100HP, the min. equivalent resistor value
for each AC motor drive is 12.5Ω with 2 brake units connection. Therefore, the equivalent
resistor value for each brake unit should be 25Ω.
7. Please read the wiring information in the user manual of brake unit thoroughly prior to taking
into operation.
8.

Definition for Brake Usage ED%

Explanation: The definition of the barke usage ED(%) is for assurance of enough time for the
brake unit and brake resistor to dissipate away heat generated by braking. When the brake
resistor heats up, the resistance would increase with temperature, and brake torque would
decrease accordingly. Suggested cycle time is one minute
9. For safety consideration, install an overload relay between the brake unit and the brake resistor.
In conjunction with the magnetic contactor (MC) prior to the drive, it can perform complete
protection against abnormality. The purpose of installing the thermal overload relay is to protect
the brake resistor from damage due to frequent brake, or due to brake unit keeping operating
resulted from unusual high input voltage. Under such circumstance, just turn off the power to
prevent damaging the brake resistor.
B-2
10 0%
T1
Br ak e Time
C yc le Time
ED% = T1 /T0 x10 0(% )
T0
Revision August 2008, 03VE, SW V2.04