
The NLSW2aS3 is used with fitting sensors (F2, F2Sond.1, F3, F4.2) to watch flows with
velocities above 10m/s, e.g. usage in chucks. Once you set up the switch-point it will be
adapted so fast changing media temperatures with reaction-time depending on the applied
sensor.
Breaks within the cable connection or a defect of the device will be signalled by broken relays
contact. The LEDs show the actual switching status.
Measuring principal
A temperature-sensitive resistor is heated according to the calorimetric measuring principle. The temperature-
sensitive resistor is heated by a second resistor. A flow dissipates heat from the measuring resistor, causing the
resistor’s temperature to fall and thus a change of impedance. This temperature change is evaluated. Since both the
velocity and the temperature of the flowing medium affect the dissipated heat, a relationship must be created
between flow and temperature. For this purpose, a second temperature-sensitive resistor is located next to the first
one. The second measuring resistor is not heated and is only used for the temperature measurement.
Airflow > / = switch point Switching output is energised Yellow LED “Airflow“ switch on
Airflow < switch point Switching output isn’t energised Yellow LED “Airflow“ switch off
Technical Data
1 change-over contact, 1 NO contact
1 change-over contact, 1 NO contact
Relay output
Minimum switching load
250VAC, 5A, 2kVA
10mA / 5V DC
250VAC, 5A, 2kVA
10mA / 5V DC
Relay energised when airflow is
present
Relay energised when airflow is
present
Signal lamp, start up delay
Switching point adjustment
protection category, housing
protection category,
terminals
Installation Instruction:
Before setting up the switching point, the device should have been active for at least 2 minutes in normal conditions.
To set up the switching point please attend the following steps:
-The sensors tip should be placed in the duct’s middle and has to be flowed around completely by the
medium.
-The flow in vertical-ducts needs to be upwards.
-To assure maximum reliability the sensor needs a length of the inlet path of 5xD (inside pipe diameter)
and 3xD (inside pipe diameter) of the outlet path.
-The sensor is to be mounted only with its own hex-head screw.
-The sensor must be connected to the evaluation unit as described in its manual. Incorrect connection
leads to malfunctioning and can destroy both!
-If the sensor’s cable is laid in a conduit with other live cables (motor-, solenoid valve-cables, …) we
recommend shielding it.
-If the length of the cable needs to be changed it needed to be done with a.w.g. 16 (1.5mm²) and must
not be longer than 50m!
Maintenance information:
In order to avoid malfunction the sensor should be maintained in regular distances according to its pollution.
Cleaning the sensor pay attention to following steps:
-Dismantle the sensor.
-Insert the sensor in slightly warm and soaped water carefully for about 10 minutes.
-Carefully rinse off the airflow sensor with lukewarm water.
-Assemble the airflow sensor.
Attention: Do not use screwdrivers or equal to clean the sensor!
Attention!!
Connection and commissioning must be performed by properly authorized and qualified personnel!
Connection to mains supply (L, N) must be made by means of a protected isolating switch with the usual
fuses. As a matter of principle, the General VDE Regulations must be complied with (VDE 0100, VDE 0113,
VDE 0160). If the potential-free contact is connected to an extra-low safety voltage, sufficient insulation
must be provided for the connecting cables up to the terminal, since otherwise the double insulation to the
mains voltage side may be impaired. The current load capacity of the potential-free contact is limited to 10
A. Therefore, the electrical circuit of the potential-free contact must be protected by a 10.3 a fuse.
Electrical connection
Colour code: BR=brown, BK=black, GR=grey