Delta Electronics AC Motor Drive VFD-EL User Manual page 178

9. For safety reasons, install a thermal overload relay between brake unit and brake resistor.
Together with the magnetic contactor (MC) in the mains supply circuit to the drive it offers
protection in case of any malfunctioning. The purpose of installing the thermal overload
relay is to protect the brake resistor against damage due to frequent brake or in case the
brake unit is continuously on due to unusual high input voltage. Under these
circumstances the thermal overload relay switches off the power to the drive. Never let
the thermal overload relay switch off only the brake resistor as this will cause serious
damage to the AC Motor Drive.
NFB
R/L1
S/L2
T/L3
O.L.
Thermal
Overload
Relay or
temperature
switch
Note1: When using the AC drive with DC reactor, please refer to wiring diagr am in the AC drive
user manual for the wiring of terminal +(P) of Brake unit.
Note2: Do NOT
Revision August 2008, 2ELE, V1.02
100%
Braking Time
Cycle Time
MC
R/L1
S/L2
T/L3
VFD Series
MC
SA
Surge
Absorber
wire terminal -(N) to the neutral point of power system.
T1
ED% = T1/T0x100(%)
T0
U/T1
IM
V/T2
W/T3
MOTOR
+ P ( )
+ P ( )
- N ( )
- N ( )
Brake
Unit
Appendix B Accessories|
Thermal Overload
Relay
B1
O.L.
Brake
Resistor
BR
B2
Temperature
Switch
B-3