Electrical Motor Control


Aoip

EPM

Description

Electrolytic starter (LRS) for slipring motors from 550 to 20,000 kW

EPM electrolytic starter can be used to start slipring motors from 500 kW to 20,000 kW. It will supply the power necessary to drive the motor by resistance variation.

  • Smooth progressive acceleration
  • Wide range of applications
  • Rugged and reliable
  • Customised for each application
  • Reduced maintenance

EPM electrolytic starter can be used to start slipring motors from 500 kW to 20,000 kW. It will supply the power necessary to drive the motor by resistance variation. Designed for controlled starting and speed control of large slipring motors in demanding applications, the EPM liquir rotor starters ensure a smooth progressive acceleration of installations such as:

  • Ventilation
  • Crushing
  • Milling
  • Conveyors
  • Pumps

They are widely used in various industries such as mines, quarries, cement plants, water treatment and associated industries. They are also adapted to specific applications such as car fragmentisers, plastic mixers and sugar cane knives.

Several models and options are available according to the starting power required, the inertia of the driven machine and the application. Feel free to contact us and explain us about your requirements (Use the section Necessary information to quote a starter),our staff will quote the suitable starter and the eventual necessary options.

You will find below the description of an EPM starter and its operating principle.


An EPM unit is made of:

  • the electrolytic resistance contained within a tank complete with electrodes of a size rated for the specific kW rating.
  • the MV enclosure housing the short-circuit contactor.
  • the LV enclosure which contains the control system.

Tank: The tank is manufactured with heavy duty sheet steel 30/10 to 50/10 mm gauge, and is normally supplied complete with lifting eye bolts Tank capacity and dimensions are determined by the motor rating.

The tank is filled through a filling flap and emptied through valves situated at the base of the unit, which are normally locked in the ‘closed’ position.

Agitator: The agitator is thermostatically controlled to ensure maximum thermal capacity.

Electrolyte: Various concentrations of sodium carbonate are normally employed. The electrolyte level is monitored by a float switch and the temperature is controlled by thermostats.

Electrode assemblies: A set consists of three fixed and three moving electrodes; polypropylene containers shroud the fixed electrodes to provide adequate isolation between phases.

The cast alloy electrodes consist of concentric cylinders which merge with each other in the minimum resistance position.

The fixed electrodes, located inside the insulating containers, are fed from an insulated copper bar. Since this bar does not pass through the tank wall, there is no danger of electrolyte leakage.

The moving electrodes travel vertically inside the insulating container, guided by a nylon rod. The assembly is supported by two brass rods fixed to a transversal carrier which is common to all three electrodes and constitutes the neutral point.

Current density is extremely low (typically 1 amp/cm²) resulting in extremely long electrode life.

Electrode control system:

Displacement of the electrodes is effected by a motor driven worm screw assembly. This is normally controlled by either a geared motor or a servomotor depending on the application.

An inverter may also be used for some applications.

A hand wheel is also provided for emergency operation.

Starting times are adjustable from 10 to 150 seconds.

Control and interlocking: Limit switches are incorporated to control the geared motor, and to power the shorting contactor which shorts out the residual resistance at the end of the run up time. The geared motor is fitted with

an overload relay, which is used to provide protection in case of the drive mechanism jamming.

An electrical interlock prevents a restart before the electrodes return to the initial maximum resistance position.

If a power failure occurs during starting, the electrodes return automatically to the start position when the supply is restored, so that a new start is possible.

Control panels: The control gear is housed in two separate enclosures. The shorting contactor complete with the rotor terminations are housed in the MV enclosure.

A separate housing is provided for the LV controls.

The MV enclosure is normally included with the starter, but for higher ratings, it may be supplied in a separate control panel.


RLV

Description

Vapormatic starters for low and medium power slipring motors up to 750 kW

RLV vapormatic starters are used when the driven machines are of great inertia or when the rating power of starting / driven machine is low.

  • Reliable: no moving parts, unaffected by demanding atmospheres
  • Economical: cable saving, reduced maintenance, competitive price
  • Customizable to specific motor requirements

RLV vapormatic starters are used when the driven machines are of great inertia or when the rating power of starting / driven machine is low. They have the following advantages:

Reliability

  • No moving parts other than the short circuit contactor
  • Unaffected by damp, dusty or corrosive atmospheres

Savings

  • Cable saving: integral contactors
  • Facilitate installation beside motors
  • Electrical and mechanical maintenance considerably reduced
  • Competitive price

Adaptability

  • Easy adjustment gives "made to measure" starting conditions and conversion to suit different drives.
  • Operating principle

    The starting principle is based on the difference in resistivity between a liquid electrolyte and its vapour, contained in an electrode chamber.

    The passage of the initial rotor current causes immediate partial vaporisation of the electrolyte and instantaneously adjusts resistance and starting torque to optimum values. During the run-up to speed, the thermal interchanges which occur progressively decrease the resistance.

    A timed contactor then short circuits the low residual resistance.

    The starting torque is determined according to the requirements of the driven machine or the current limitation.


    NS3

    Description

    Electronic starter for low and medium power cage motors

    The soft electronic starter NOVADEM S3 (NS3) is designed to control all aspects of starting, stopping and protection of 3 phase squirrel cage motors up to 1200 kW at 690 V.


    The soft starter NOVADEM S3 (NS3) is designed to control all aspects of starting, stopping and protection of 3 phase squirrel cage motors up to 1200 kW at 690 V.

    These high performance digital starters offer a user interface that supports a quick programming method by using pre-configurated application macros.

    The NS3 also features as standard a RS232 serial link to communicate with a PC or a network.

    The NS3 starters allow a progressive starting, protection and stopping (freewheel, regulated or quick) of any three-phase asynchronous motors over a large range of power.

    The NS3 user interface is made of:

    • A user-friendly display and keyboard interface for quick programming of every application by selecting the appropriate macro-programming
    • A RS 232 serial link to connect it to a PC or a network

    The powerful software enables the starter to be programmed and maintained without the constant need for an operating manual.


    RED

    Description

    Electrolytic starters for low and medium power cage synchronous motors

    RED statormatic electrolytic starters for cage motors offer an unrivalled starting capability up to 750 kW.

    • Reliable: no moving parts, no current peak during starting process
    • Economical: reduced maintenance
    • Customizable to specific motor requirements

    RED statormatic starters offer an unrivalled starting capability and have the following advantages:

    Reliability

    • They do not have any moving parts other than the short circuit contactor
    • There is no current peak at the end of the starting period

    Economy

    • Electrical and mechanical maintenance considerably reduced
    • Units pre-wired

    Adaptability

    • The starting characteristics are "made to measure" and can be altered for a change of motor or machine by simply replacing the electrolyte.

    Description

    The starters of this range can be supplied in three formats: RC, RW or RZ. They are made up of two parts:

    • The electrolytic starting resistance in a frame with tanks and a thermostat.
    • The equipment:
      • An enclosure integrated into the frame which contains a short circuit contactor, a timing relay, eventually a line contactor or further option. The RC and RW units are supplied in this format.
      • A separate WS wall mounting enclosure can be used with RZ frames. The RZ/WS modular assemblies are prewired.

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