low-voltage

2
Squirrel-cage motors
Technical information
Modular technology
■ Brakes
Spring-operated disk brakes
are used. Depending on the
motor selected, brake types
2LM8 or KFB are used. Standard
brakes are for connection
to 230 V and delivered with a
rectifier.
Order Code G26.
2LM8 spring-operated disk
brake
This brake is fitted to 1LA5 and
1LA7 motors with frame sizes 63
to 225 and to 1LG motors with
frame sizes 180 to 200 as standard.
Design and mode of operation
The brake takes the form of a
single-disk brake with two friction
faces.
The braking torque is generated
by friction when pressure is applied
by one or more compression
springs to the de-energized
brake. The brake is released
electromagnetically.
When the motor brakes, the rotor
- which can be axially shifted
on the hub or the shaft - is
pressed via the armature disk
against the opping frictional surfaces
by means of the springs.
When the brake is applied,
there is an air gap SLü between
the armature disk and the solenoid
component. The solenoid
coil is energized with DC voltage
in order to release the
brake. The resulting magnetic
force pulls the armature disk towards
the solenoid component
against the spring force. The
spring force is then no longer
applied to the rotor, so that the
latter is able to rotate freely.
Voltage and frequency
The solenoid coils and the rectifier
of the brakes are designed
for connection to the following
voltages:
1 AC 50 Hz 230 V ± 10% or
1 AC 60 Hz 230 V ± 10%.
It is not permissible to increase
the brake voltage at
60 Hz!
The brake can also be supplied
for other voltages. Brake connection
voltage:
24 V DC Order Code C00
2x 400 V AC Order Code C01
Order Codes C00 and C01 must
only be used in conjunction with
Order Code G26.
2/50
Siemens M 11 · 2003/2004
Rating plate
The motors have a second rating
plate with the brake data on
the opposite side of the motor.
The 2LM8 brake is designed in
IP55 degree of protection.
Please enquire if the brake motors
are used at subzero temperatures
or in very humid environments
(e.g. in a maritime climate)
with long downtimes.
Connection
The main terminal box of the
motor contains labeled terminals
for connecting the brake.
The AC voltage for the excitation
winding of the brake is connected
to the two free terminals
of the rectifier block (~).
The brake can be released
when the motor is stationary by
separately energizing the solenoid.
In this case, AC voltage
must be connected to the terminals
of the rectifier block. The
brake remains released as long
as this voltage is present.
The rectifiers are protected
against overvoltages by means
of varistors at the input and
output.
The terminals of the brakes for
24 V DC voltage are connected
to the DC voltage source
directly.
Fast brake application
The brake is applied when it is
isolated from the supply. The
application time of the brake
disk is delayed by the solenoid
coil inductance (disconnected
on the AC side). This involves a
significant delay. For short
brake application times, the
brake must be disconnected on
the DC side. For this purpose,
the jumper between contact 1+
and contact 2+ must be removed
and replaced by the
contacts of an external switch
(see circuit diagrams).
Mechanical manual release
The brakes can be supplied
with a mechanical manual release
using an actuator lever.
Order Code K82.
The length of the motor is increased
by dL due to mounting
the brake. For dimensions see
Page 2/56.
6
1
4
1 Armature disk
2 Compr. springs
3 Ax. sliding rotor
4 Hub
5 Shaft
6 Opposing frictional
surface
7 Solenoid comp.
Design of the brake
S
LÜ
3 2
SA1-5018
Half-wave rectifier 400 V AC
,
8 , 8
# "
Rectifier bridge 230 V AC
, ,
, "
8
, !
# "
Brake connection with 24 V DC voltage
L+ L-
M1-5179
8
7
2
5