Monitoring Relays
Tachometer
Type SM 155
Specifications are subject to change without notice (13.03.01) 1
• Tachometer relay
• Measuring ranges:
30 - 300 R.P.M.
200 - 2000 R.P.M.
1000 - 10000 R.P.M.
• Knob-adjustable set level
• Controlled by Namur/DIN 19234 sensor or metallic
contact
• Connection for moving-coil instrument
• 10 A SPDT output relay
• LED indication for relay ON
• AC or DC power supply
Product Description
SM155 monitors the actual
RPMs of a motor by a
Namur/DIN 19234 sensor or
a metallic contact.
Knob adjustable set level on
relative scale.
Type Selection
Plug Output Measuring range Supply: 24 VAC Supply: 115 VAC Supply: 230 VAC Supply: 24 VDC
Circular SPDT 30 - 300 R.P.M. SM 155 024 300 SM 155 115 300 SM 155 230 300 SM 155 724 300
11 pins SPDT 20 - 2000 R.P.M. SM 155 024 2K SM 155 115 2K SM 155 230 2K SM 155 724 2K
SPDT 1000 - 10000 R.P.M. SM 155 024 10K SM 155 115 10K SM 155 230 10K SM 155 724 10K
Input Specifications Output Specifications
Input
Through terminals:
Metallic contact: 5, 6
Namur sensor: 6, 7
Measuring ranges
Types:
300: 30 to 300 R.P.M.
2K: 200 to 2000 R.P.M.
10K: 1000 to 10000 R.P.M.
Inversion Interconnecting pins 8, 11
Short circuit current
Pins 5, 6 5 mA
Pins 6, 7 10 mA
Connection cable Can be extended as desired
Max resistance 100 Ω
Hysteresis approx 3% of set value
Output SPDT relay
Instrument connection Connection for moving-coil
instrument
Through pins 8, 9, pin 9 positive
Full scale deflection 1 mA
Internal resistance 110 Ω
Rated insulation voltage 250 VAC
Contact ratings (AgCdO) µ
Resistive loads AC 1 10A, 250 VAC
DC 1 1 A, 250 VDC
Small inductive loads AC 11 2.5 A, 230 VAC
DC 11 5 A, 24 VDC
Mechanical life ≥30 x 106operations
Electrical life ≥2.5 x 105operations
(at max load)
Operating frequency ≤7200 operations/h
Dielectric strength
Dielectric voltage ≥2 kVAC (rms)
Ordering key SM 155 230 10K
Housing
Function
Output
Type
Power upply
Measuring range
SM 155
2Specifications are subject to change without notice (13.03.01)
Supply Specifications
Mode of Operation/Level Setting
General Specifications
Power supply Overvoltage cat. III
Rated operational voltage (IEC 60664, IEC 60038)
Through terminals 2, 10
024: 24 VAC ± 15%, 45 to 65 Hz
115: 115 VAC ± 15%, 45 to 65 Hz
230: 230 VAC ± 15%, 45 to 65 Hz
724: 24 VDC ± 15%
Dielectric voltage 2 kV
Transient protection > 3kV
Rated operational power
AC models 4 VA
DC models 2 W
Reaction time Time between 2 pulses at
the set value of the poten-
tiometer
Accuracy of measurement ±3%
Indication for
Power supply ON LED, green
Output relay ON LED, red
Environment
Degree of protection IP 20
Operating temperature -20 to +50°C
Storage temperature -50 to +85°C
Housing dimensions 35 x 80 x 83 mm
Weight
AC power supply Approx. 200 g
DC power supply Approx. 125 g
Approvals UL, CSA
CE Marking Yes
Wiring Diagrams
Ex. 1, 2 - Mechanic triggering with metallic contact Ex. 3, 4 - Electr. trig. with NAMUR/DIN 19234 sensor
The relay is controlled by
mechanical triggering, e.g.
microswitch, reed relay, limit
switch etc. (examples 1 and
2), or by electronic trigger-
ing, e.g. inductive or capaci-
tive sensors (NAMUR/DIN
19234) (examples 3 and 4).
Examples 1 and 3
The relay operates when the
number of R.P.M. exceeds
the set value.
The relay releases when the
number of R.P.M. is less than
the set value. See hysteresis.
Example 2 and 4
By interconnecting pins 8
and 11 the relay function is
inverted, i.e. the relay releas-
es when the number of
R.P.M. exceeds the set
value.
The relay operates when the
number of R.P.M. is less than
the set value. See hysteresis.
Instrument connection
A moving-coil instrument
with a scale calibrated in
R.P.M. can be connected to
the SM 155. The instrument
has 1 mA full scale deflec-
tion.
The relay generates max. 8.2
V on the instrument termi-
nals (pins 8 and 9) across an
internal resistance of 8.2 kΩ
in the relay. The ideal internal
resistance of the instrument
is 110 Ω. A deviation in the
internal resistance of ± 100
Ωresults in an error of ± 1%.
Level Setting
Knob adjustable on relative
scale
SM 155
Specifications are subject to change without notice (13.03.01) 3
Operation Diagram
