Switching unit for conductivity sensors

Nivotester FTW325

11-35 Pcs.



  • Easy wiring with terminal blocks

  • Configurable sensitivity range

  • Intrinsically safe signal circuit EEx ia IIC for using sensors in

    hazardous areas

  • Alarm relay can be switched as second level relay (SPDT)

Product: Liquids ≥ 5 S/cm


ATEX II (1) GD EEx ia

Feeding sensors:

Conductive rod or rope sensors

Product/VersionPrice/pcs. in NZ$Order code
Nivotester FTW325
Power SupplyApprovalSwitch Output1 to 34 to 1011 to 35
85-253VACNon-hazardous area1x SPDT level + 1x SPST alarm220.-205.-194.-FTW325-A2A1A
The above models are ex stock. Please ask for pricing and delivery time of other FTW325 versions.

Prices are net, ex store Auckland, GST additional and valid until 30/9/2016.
EMC's standard Terms and Conditions of Supply are applicable.


The Nivotester FTW325 can be used for overspill protection (WHG), pump dry running protection or as a two-point control for pumps. Sensors such as the Liquipoint T FTW31 can be connected to the FTW325. Multipoint detection for up to five measuring points is possible by using 3 Nivotester FTW325s.


The intrinsically safe signal input of the limit switch Nivotester FTW325 is galvanically isolated from the mains and the output. The Nivotester supplies the conductivity probes with an alternating current via a two or three-wire line and monitors its voltage. If the product reaches the switch point of the probe, the voltage between the probe and Nivotester is reduced. The output relays at the Nivotester switch depending on the set failsafe mode. Two yellow LEDs on the front panel of the Nivotester indicate the relay switch status.  

Application Example

a) FTW325 - Proberod1

Technical data

  • Measured variable
Depending on the setting selected, the limit signal is triggered at a minimum or maximum level
  • Measuring range

Three resistance ranges can be set with DIL switches; 0.1 to 1.0 kΩ; 1.0 to 10.0 kΩ; 10.0 to 200.0 kΩ

  • Input signal
Input galvanically isolated from power supply and output
  • Type of protection
[EEx ia] IIC
  • Output signal
Relay output: one floating changeover contact for the level alarm
  • Alarm relay
Floating changeover contact for fault reporting, can be switched as second level relay
  • Switching delay
0.5 s; 2.0 s; 6.0 s when relay energized
  • Switching power of relay contacts

Umax 253 V;

Imax 2 A;

Pmax 500 VA at cos φ ≥ 0.7;
Umax 40 V;

Imax 2 A;

Pmax 80 W

  • Function indicators
Light emitting diodes for operation (gn), fault (rd), level alarm 1 (ye) and level alarm 2 (ye) light up when level relay is energized
Power supply
  • Supply voltage

85 to 253 V AC, 50/60 Hz;

20 to 30 V AC / 20 to 60 V DC, max. 60 mA

  • Power consumption

AC-version maximum 4.5 VA

DC-version maximum 1.2 VA (at Umin 20 V)

Operating conditions
  • Ambient temperature
For individual mounting -20 to +60 C for series mounting without lateral spacing -20 to +50 C
  • Storage temperature
-25 to +85 C
(preferably at +20 C)
  • Installation in protective housing
-20 to +40 C
  • Ingress Protection
IP 20
  • EMC
Interference emission to EN 61326; electrical equipment Class B; interference immunity to EN 61326; Annex A (industrial) and NAMUR recommendation NE 21 (EMC)
Electrical connection
  • Connection line
two core, screening not required
  • Line resistance
max. 25 Ω per core
  • Cross-section
max. 12.5 mm or 21.5 mm
  • Ex approval

ATEX II (1) GD [EEx ia] IIC

  • WHG approval

Overspill protection to 19 WHG (Germany)

Dimensions (in mm)

Mounting on DIN rail (EN 60715 TH35)

Installation according to instruction manual

Electrical connection


b) Power supply

c) Level relay 2/Alarm relay