OPERATING MANUAL for
BRAKE UNITS
JB10/... JB16/... JB26/... JB40/... JB52/...
(Installation set)
JB
6 of 19
01.96/00/Scho
5 PURPOSE
JB brake units are intended to brake manufacturers' unbalanced motors
or three-phase motors used in conjunction with vibrating machineries.
In conjunction with an existing motor control system, or one to be
installed separately, the JB brake unit is used to shorten the coasting
period of the machine after it is switched off. Generally, machines with
one or two drives can be braked. More than two drives are possible in
special cases.
By virtue of its design, vibrating machinery can generate very high,
undesirable vibrations if motor coasting is unbraked, when passing the
transient frequency. When a JB brake unit is used, the motors can be
braked to a standstill quickly and effectively, so that the undesirable
frequencies are either strongly attenuated, or do not occur at all.
6 OPERATING
PRINCIPLE
The JB brake unit operates fully electronically. A thyristor in a phase
controlled system generates an adjustable direct current in conjunction
with the electronic control logic. The control logic ensures that the direct
current does not reach the stator, through a braking contactor, until the
motor has been switched off. Said direct current creates a static
magnetic field, which counters the rotary movement of the rotor.
Automatic detection of standstill ends the braking process.
Stator windings are connected in series through the braking contactor, if
more than one motor is to be braked (see connection diagram in the
appendix).
Operating sequence:
(One motor application; on the basis of the connection diagram in the appendix):
If the brake unit is live from the mains, the LED "P" (mains) will light.
Contact 3/4 is broken and n2/n4 made. When the motor starts,
contactor K2 is locked. The brake unit receives the "motor on" signal
from the motor contactor through connection 6/7. LED "M" (motor on)
thus also lights. Contact n2/n4 (= restart lockout) breaks
simultaneously.
When the motor stops, contactor K2 drops out. The contact at 6/7
breaks. LED "M" goes out. After a short delay, contact 3/4 closes and
LED "B" (braking on) lights. Contactor K1 picks up and the braking
current flows through the motor winding, initiating braking. LED "S"
(standstill display) lights during the braking process until the motor
comes to a standstill. The braking process will be ended, unless the
braking time has been extended with trimming potentiometer "T".
Contact 3/4 breaks, contactor K1 drops out and LED "B" goes out.
Contact n2/n4 is then made again. Only now is it possible to restart the
motor.
