WIKA NWU-1 Serie Mode D'emploi page 7

7. Starting, operation
Electrical connection
Earth the housing, through the process connection, against electromagnetic
!
fields and electrostatic discharge.
Warning
 Ground the cable screen at one end, preferably in the safe, thus non-Ex,
area (EN 60079-14). For devices with flying leads, the screen is connected
to the housing. The simultaneous connection of housing and cable screen
Warning
to ground is only permitted if ground loop problems between the screen
connection (e.g. at the power supply) and housing can be excluded
(see EN 60079-14).
For a tansducer with „Ex nL IIC T4" certification, it should be powered from an energy-

limited 4 ... 20 mA current loop.
For a tansducer with „Ex nA IIC T4" certification, it should be connected to a supply

and signal circuit with transient voltage protection in accordance with EN 60079-15
Chapter 12 C.
 Consider both the internal capacitance and inductance.
 Cover flying leads with fine wires by an end splice (cable preparation).
Ingress protection per IEC 60529 (The ingress protection classes specified only apply

while the pressure transmitter is connected with female connectors that provide the
corresponding ingress protection).
Ensure that the cable diameter you select fits to the cable gland of the connector

Ensure that the cable gland of the mounted connector is positioned correctly and
that the sealings are available and undamaged. Tighten the threaded connection and
check the correct position of the sealings in order to ensure the ingress protection.
Please make sure that the ends of cables with flying leads do not allow any ingress of

moisture.
 The transducer must be connected and operated in accordance with the approriate
regulations. Take care to ensure that the electrical connection (e.g. M12 connector) is
correctly made (fully sealed).
10 WIKA Operating instructions/Betriebsanleitung/Mode d'emploi/Instrucciones de servicio NWU-1
GB
7. Starting, operation
For equipment with Ex nA certification, or if operated under nA conditions:
Never disconnect the equipment when it is powered!
Warning
The WIKA NWU Series transducer is designed to operate with an input voltage of
10 VDC < U ≤ 24 V. The voltage value Ui = 24 V DC shall not be exceeded in the current loop
B
circuit. The interrelationship between voltage supply and load resistor (R
following diagram.
Signal output and allowed load
4 ... 20 mA, 2-wire
permitted
range
Current for external display- or evaluation equipment can be supplied directly from the circuit,
when operating a transducer with current output. A voltage drop specific to the display unit is
to be considered. The UHP-display unit of type WUR-1 has a specific voltage drop of 6 V. The
transducers are short-circuit-proof for a short time, but anyhow any incorrect connection of
the instrument should be avoided.
Power supply
UB+/Sig+ Positive supply / measurement connection
OV/Sig- Negative supply / measurement connection
WIKA Operating instructions/Betriebsanleitung/Mode d'emploi/Instrucciones de servicio NWU-1
S
) is illustrated by the
A
Output current (2-wire)
4 ... 20 mA:
R ≤ (U – 10 V) / 0,02 A
A B
with R in Ohm and U in Volt
A B
Load (e.g. display)
GB
11
S