Electronic V-belt monitoring device
EKW 2.3.x.x / EKW 2.3.x.xA
Areas of application
These devices are used in ventilation and air conditioning
systems for the reliable monitoring of V-belts. DDC control
technology and intelligent control systems have meanwhile
become standard. Therefore, the demand for more opera­
tionally reliable and modern belt monitoring has become more
urgent. Especially with speed-controlled fans, there is no better
monitoring for V-belts.
Principle of operation
Technical data
Housing: Mounting
rail attachment:
Terminals:
Ambient temperature:
Dimensions:
Protection class:
Ambient humidity:
High impact polystyrene
for TS 32 and TS 35
pluggable to the base plate
0 °C to + 40 °C
96 x 48 x 60 mm (L x W x D)
IP 40
Class F according to DIN 40040 for
components
Working range:
100 – 9.000 rpm
Setting range:
100 – 6.000 rpm
Operating principle:
lower deviation
Voltage:
EKW 2.3.1 230 V 10 %, 50 – 60 Hz
EKW 2.3.2  24 V 10 %, 50 – 60 Hz
Current consumption: 50 mA, including sensor
External fuse protection: max. 1 A
Switching hysteresis:
5%
Breaking capacity:
Relay 3 A 250 V, AC-1
Outputs:
2 changeover contacts
Supply voltage:
15 – 18 V DC
Sensor:
between terminal 14 and 16
Analog output:
EKW 2.3.1..A1: 0 – 10 V, max. 2 mA
EKW 2.3.2..A2: 4 – 20 mA
An electronic proximity sensor mounted on the fan housing
sensor detects the rotation of the fan shaft through the detection of a retaining screw mounted on the fan shaft by means of
a tension band. When a metal part (tensioning screw) passes
by the sensor face, the electromagnetic field is broken and an
impulse is created. These are analyzed in the control unit. If the
rotation speed falls below the set value, the relay drops out.
For use in explosion-risk areas, Namur sensors are used, whose
signals are delivered via an additional Ex-amplifier to the electronic V-belt monitor.
The device is ready for operation when the voltage is applied,
and the relay is energized. In parallel to the fan, the release
contact is opened and the control unit starts. First the startup bridging takes place for 60 seconds, the relay is forcibly
energized, contacts 4 – 5, 7 – 8 are closed. After the start-up
bridging sequence, the relay remains energized as long as the
rotation speed exceeds the limit, and drops out if the speed falls
below it. Then a compulsory interlock takes place as long as and
until the fault is eliminated and the release is carried out on the
device with the key button , or externally either individually
or centrally.
Sensor ventilation air conditioning | Data sheet No. 10102 | Version 07-2008_1 | 1
Electronic V-belt monitoring device EKW 2.3.x.x / EKW 2.3.x.xA
Analog output
Installation
Only for models with the suffix “A”.
Bring the fan with a secure V-belt to full rotation speed. Then
adjust “Anpassung” with the potentiometer  10 V or 20 mA.
A clockwise rotation of the 12-gang-shaft potentiometer causes
a decreasing signal. With a multimeter’s probes the measuring
signal is easy to tap at the terminals.
Behind the front panel is a green LED , that glows lighter or
darker according to the output signal.
The switching device is to be snapped on mounting rails in a
switching cabinet in the equipment room with its click-in base.
The distance from device to device and to heat-emitting relays
etc. must be at least 2 mm.
The back-of-hand-proof connection terminals are to be inserted
from top to bottom in the housing socket board and therefore
provide adequate protection against contact.
Since the devices are installed in a dust-proof cabinet, they do
not require cleaning. Should it still be necessary, it should be
carried out with a dry brush. The operating license is valid only if
the above mentioned operating instructions are followed.
Opening the housing or damaging the warranty seal will void
the warranty.
Note: The analog output is only adjustable at speeds
of 100 – 1000 rpm.
Higher ranges on request.
Dimensional drawing
Dimensions in mm
Adjusting the threshold
With the DIP switches , which are accessible behind the open­
ings in the front panel, the rotation speed range is preselected
(View is with the company logo at the top):
DIP-switch left: down, right: down
Range 1:
100 – 1000 rpm
DIP-switch left: down, right: up
Range 2:
1000 – 2000 rpm
DIP-switch left: up, right: down
Range 3:
2000 – 4000 rpm
DIP-switch left: up, right: up
Range 4:
4000 – 6000 rpm
LED Functions
Yellow LED : Start-up bridging
Green LED : Flashes with the impulse of the sensor,
as long as the set rotation speed is too low.
Green LED : Continuous, set speed is exceeded,
operating state.
Red LED :
Fault, rotation speed is too low.
If the red and green LEDs light up together, the fan shaft is
positioned with the hose clamp’s screw directly over the front
surface of the sensor.
If the yellow and green LEDs light up together, the shut-down
speed has already been exceeded during the start-up phase.
With this it is clearly recognizable that the transfer from the
sensor to the controller is functioning properly.
If during the start-up phase the green LED does not flash in
time with the impulse frequency, there is a communication
problem between the sensor and control unit, or the fan is not
running.
The adjustment potentiometer  is located behind the front
panel (marked “Schwellwert”) with a 340° rotation. The slot in
the shaft is easily accessible through the hole with a 3 mm
screw­driver. The left position corresponds to the upper
threshold of the preselected range; the right position corresponds to the lower threshold (lower deviation functional
principle).
Factory setting: Range 1, right position, 100 rpm.
2 | Sensor ventilation air conditioning | Data sheet No. 10102 | Version 07-2008_1
Electronic V-belt monitoring device EKW 2.3.x.x / EKW 2.3.x.xA
Connection diagram
Specification text
Only insulated circuits may be connected, i.e. only devices may
be connected which do not have any accessible energized
parts. The devices to be switched must be consolidated in a
switching cabinet. When connecting the terminals, the stranded
wires must be provided with ferrules so that no stranded wire
ends can touch terminals with different polarity.
Electronic V-belt monitor for monitoring the V-belt fan drive shaft.
Built-in time-delay relay (60 s) for start-up bridging of the drive
motor. Visual indication of operating conditions (start-up,
operation, fault) with light emitting diodes (LEDs). With adjustable shut-down speed (100 – 6000 rpm). In case of a fault, a
shut-down of the motor and self-interlock takes place. Release is
possible with a reset button on location and/or internally. With
click-in base for mounting on DIN rail.
Dimensions: 96 x 48 x 60 mm (L x W x H).
Output: 1 relay with 2 changeover contacts.
Supply voltage 230 V ± 10 %, 50 – 60 Hz, EKW 2.3.1
24 V ± 10 %, 50 – 60 Hz, EKW 2.3.2
With additional analog output:
If the rotation speed drops below 100 rpm, the analog output
abruptly goes to 0 V or 0 mA.
230 V ± 10 %, 50 – 60 Hz, 0 – 10 V, EKW 2.3.1.A1
24 V ± 10 %, 50 – 60 Hz, 0 – 10 V, EKW 2.3.2.A1
230 V ± 10 %, 50 – 60 Hz, 4 – 20 mA, EKW 2.3.1.A2
24 V ± 10 %, 50 – 60 Hz, 4 – 20 mA, EKW 2.3.2.A2
Complete with accessories.
Brand: Oppermann Regelgeräte GmbH
Supply voltage
NC NO
1
2
3
C
4
5
NC NO
6
7
O
8
K = Release contact
from the motor
contactor with
2-speed fan
contacts in series
S = reset button, only if
desired
9 10 11 12 13 14 15 16
S
Analog
output with
version “A”
K
blue black brown
Sensor
black black
Sensor
Connections
interchangable
Contact depictions are with the
power off – relay
de-energized.
Operational readiness after voltage
is applied – relay
energized.
Oppermann Regelgeräte GmbH | Im Spitzhau 1 | 70771 Leinfelden-Echterdingen, Germany
Phone +49 711 72723560 | Fax +49 711 7280527 | info@oppermann-regelgeraete.de | www.oppermann-regelgeraete.de
Specifications subject to change. Sensor ventilation air conditioning | Data sheet No. 10102 | Version 07-2008_1 | 3