+90 312 251 22 00

Current Controlled Switch / UNICONT PKK®


The members of the UNICONT PKK-312 series are 4–20 mA current controlled limit switches featuring galvanic isolation and also available as an intrinsically safe associated apparatus. The input 4–20 mA signals can be transferred from passive or active outputs of 2- or 4-wire transmitters.
The value of the input signal will be compared in the unit with the set (taught) value and the state of the galvanically isolated relay changes in accordance with the comparison mode programmed. The double throw output relay can be programmed for the following functions: Limit switch (high or low fail safe) ON-OFF control with selectable switching difference Monitoring of discontinuity or short-circuit of the cable Window comparison operation mode with energised or de-energised relay state The UNICONT PKK-312-8 Ex is a special version, designed to operate with NIVELCO’s Ex rated, DC powered 2-wire NIVOSWITCH vibrating fork level switches, as an intrinsically safe power supply and amplifier unit. Without doing any programming the galvanic isolated limit switch is able to perform relay switching signal based on the monitoring of the vibrating fork’s output current changes between the freely vibrating and the immersed states.


  • Suitable interface for devices having 4…20 mA or on-off outputs
  • Can power 2-wire transmitters
  • Galvanic isolation
  • 4…20 mA input
  • Power relay (SPDT) output
  • Limit, differential or window switch capabilities
  • Programmable damping
  • Explosion-proof models


  • Power supply and switching amplifier for 2-wire transmitters
  • Switching amplifier for 4-wire active transmitters
  • Dedicated switching amplifier version for the RC-400 range of Ex rated vibrating forks
  • Wire state monitoring
  • ON-OFF control


Power supply:110 V, 230 VAC, 24 VAC/DC
Ambient temperature:−25°C…+55°C
Input:4…20 mA
Output:Switch rating: 250 VAC, 8A, AC1
Process connection:DIN rail mounted (module width: 36 mm)
Ingress protection:IP20