The liquid rheostats have the function to carry out a soft starter and speed regulation of tree phases slip-ring asynchronous motors.


Compared to those made of metallic resistances, offer the following advantages:

• Steples resistance variation.
• Maximum assurance.
• Minimum maintenance.
• Possibility to varying the maximum resistance degree modifying the electrolyte concentration.Rispetto a quelli costituiti da resistenze metalliche offrono i seguenti vantaggi.


The continuous variation of resistance value during starting time avoids sudden current variations, and consequently a torque, which are verified instead at each step exclusion in metallic resistance rheostats.

Actually are built two series of rheostats in order to cover all needs of starting and slipping of motors between 500 and 15000 kW, and are:

  • RLM: Mobile electrodes rheostat
  • RLP: Mobile electrodes rheostat with forced electrolyte