STI SR125SMS Operating Instructions Manual

SCIENTIFIC TECHNOLOGIES INC.
R
SR125SMS
Operating Instructions for SR125SMS Stop Motion Sensing Unit
Dimensions / Encombrements
120 mm
(4.72 in)
90 mm
(3.54 in)
Terminal marking / Repérage des bornes / Klemmenanzeiger
A1
A1/A2
Ch.1
Ch. 2
Zero Speed
Ch.1
+
Ch.2
Y33/43 Y34
A2 Y44
/ Maße
Z 1
2 1
1 3
A 1
R
Z1
21
13
A 1/ A 2
A 1
14 22
C h. 1
Y 34 Y 44
ee d
Y 33 /4 3 Ze ro Sp
A1 /A 2
C h. 2 A 2
pe ed
Ze ro S
C h. 1
+
C h. 2
Y 3 4
3
Y 3 3 /4
13 21 Z1 Z3
Z2
14 22
Application
Safety systems are comprised of many components. No one safety component will
ensure the safety of the system. The design of the complete safety system should be
considered before you begin. It is very important to follow applicable safety
standards when installing and wiring these components.
The safety relay is used for stop motion detection of electric motors. Its
SR125SMS
primary use is in systems requiring the reversing of a motor and for unlocking doors
and guards with safety interlocking devices.
"Stop motion" may not indicate absolute zero speed. This device detects speeds
below user adjustable values.
When coasting to a stop, electric motors generate a residual voltage in their
windings, resulting from residual magnetism, and this decreases proportionally to the
decrease in motor speed. This residual voltage is monitored by the SR125SMS safety
relay to detect the motor's zero speed. The wiring between the motor windings and
the safety relay are also monitored, to identify a wire break (fault) differently from a
zero speed detection.
The SR125SMS safety relay is designed for Stop motion detection in all types of
electrical machinery using DC or AC, single phase or three phase power, when the
electric motors coasting to a stop generate a residual voltage. The use of electronic
motor controls such as variable speed drives, soft starters or electronic DC motor
brakes is possible, provided that they do not emit any voltage after stop. When using
electronic motor controls, refer to the paragraph "Use of electronic motor controls".
The SR125SMS is not compatible with wound rotor motors, and should not be used with
them.
Function
The supply voltage is applied to the terminals A1-A2 according to the value indicated
on the module nameplate. The LED labeled A1/A2 in the cover of the SR125SMS will
be on when the supply voltage is applied. The solid state output Y33-Y34 switches,
indicating "Supply voltage is applied".
Wiring the module to the motor
Single channel connection
The winding of the motor is connected to terminals Z1 and Z2. Terminals Z1 and Z3
have to be jumpered.
Two channel connection
The windings of the motor are connected to terminals Z1, Z2, and Z3. Terminals Z1
and Z3, being the input terminals of the SR125SMS, have to receive the same
Z 3
information from the motor, and in the most simple application both Z1 and Z3 can be
connected to one branch of the windings. Terminal Z2 is a shared input terminal of
the safety relay. When selecting the motor winding to be monitored, make sure the
Z 2
motor winding selected stays connected to the SR125SMS safety relay under all
5 S M
S R 1 2
conditions so that it cannot be short circuited or disconnected.
A dj us t.
el 1 The wiring between the input terminals of the module and the motor is constantly
C ha nn
Z2 Z3 monitored to verify proper operation by monitoring resistances, so that even when
A dj us t.
el 2
C ha nn one wire is disconnected no zero speed signal can be generated. When all
connections are correct and when the motor is at zero speed, both internal relays K1
and K2 pick up and close the hard contacts between terminals 13-14. At the same
time, the hard contacts between 21-22 are opened. Motor zero speed is indicated for
each input circuit separately and additionally as a joint signal by three LED 's in the
cover of the device. In addition to the joint signal LED "Zero speed Ch.1 + Ch.2", the
solid state output between terminals Y43-Y44 is also activated. Both of the LED's
"Channel 1" and "Channel 2" are used for adjusting the SR125SMS module as
described in "Adjusting the potentiometers" if necessary.
When the motor is started, the internal relays K1 and K2 immediately drop in voltage,
and open the output terminals 13-14 and close the output terminals 21-22. Then the
LED's indicating zero speed go out and the solid state output terminal switches off.
The serial connection between the output terminals 21-22 and the starting circuit of
the motor allows the machine control to check the correct working of the
module and its unlock output terminal between terminals 13-14 every time the motor
is started.
When the motor is turned off and is coasting to a stop, it generates a residual voltage
which is proportional to the motor speed and which is measured at the motor winding
with the highest number of windings and then monitored by the input terminals Z1-Z2
and Z3-Z2. When the motor speed decreases and the voltage generated in the
motor windings fall below the threshold value U
K1 and K2 pick up, close the output circuit between terminals 13-14 and at the same
time open the output circuit between terminals 21-22. The solid state output
terminals Y43-Y44 switches and indicates "motor zero speed".
Using electronic motor controls
When using electronic motor controls (e.g.: variable speed drives), it must be
considered that some of these components carry out an initial measurement
procedure at the motor windings once the voltage is applied, to insure correct
application and control. This measurement procedure may be interpreted by the
module as a signal for residual voltage, depending on the voltage level and
SR125SMS
duration of the measurement sequence, and may de-activate one or both input
SR125SMS
(see diagram) both internal relays
s