R&M Materials Handling VARIABLE SPEED CONTROLS ControlMaster Plus Service Manual - Manual (Page 24)

R&M Materials Handling, Inc.
4501 Gateway Boulevard
Springfield, Ohio 45502
P.: (937) 328-5100
FAX: (937) 325-5319
24/83 R&M Materials Handling, Inc. reserves the right to alter or amend the above information without notice.
1.17.2 ESD141
Brake control unit ESD141 is a line voltage full/half-wave rectifier for DC-brakes.
1 2 3
4
5
6 7
K7
K7
Set 0.3s
Brake
K7
K7
E
S
D
1
4
1
AC Line Voltage
K7
Voltage range 200...690Vac
Output voltage U
DC
Full wave 0.90 x U
AC
Half wave 0.45 x U
AC
Maximum current 1.25Adc continuous and 2.5Adc at ED5%
When the brake is opened, the brake contactor K7 connects two phases of mains
voltage to terminals 1, 2 and 3, which makes the device a full wave rectifier. The full
wave mode is used to get the brake open fast. In addition, the brake contactor shorts
terminals 4 and 5 thus making the DC-circuit.
After a time delay (normally 0.3s), the delayed contact of the brake contactor opens,
which disconnects the supply from terminal 3 and the rectifier changes to a half wave
type. Half wave operation prevents heating of the brake coil and is enough to keep the
brake open.
To close the brake, the brake contactor disconnects the supply to terminals 1 and 2. The released brake contactor also
opens the brake coil DC-circuit, which speeds closing of the brake. The purpose of the varistor there is overvoltage
protection for K7 contacts and the brake coil.