# Liquid Starter

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In current business project I have to supply a motor and a liquid starter.

To achieve true understanding i need some information.

The motor descriptions are as below:

Rated power (kW): 1500

Rated torque (Nm): 9600.5

Rated voltage (V): 3300

Rated speed (rpm): 1492.00

Number of poles: 4

Rated frequency (Hz): 50.00

Rated current (A): 305

Moment of inertia (kgm2): 115.00

Rotor voltage (V): 1810

Rotor current (A): 498

According to supplier voltage & current needs of the Liquid starter are:

400 V 3AC 10 A

Dimensions are Approx. 1600 x 1400 x 2000.

I have read about how they work, but I need to know exactly what is happening.

There are 3 electrodes in liquid starter that they come down. In top position resistance is Max and gradually by coming down resistance decrease. In this phase the current goes to rotor. The rotor begins to turn. When the R(min) is reached the starter short-circuits and the main power will flows to motor (stator).

I don’t realize how the rotor V is 1810 when motor is 3300?

Is rotor begins to turn while the electrodes coming down?

Thanks

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In current business project I have to supply a motor and a liquid starter.

To achieve true understanding i need some information.

The motor descriptions are as below:

Rated power (kW): 1500

Rated torque (Nm): 9600.5

Rated voltage (V): 3300

Rated speed (rpm): 1492.00

Number of poles: 4

Rated frequency (Hz): 50.00

Rated current (A): 305

Moment of inertia (kgm2): 115.00

Rotor voltage (V): 1810

Rotor current (A): 498

According to supplier voltage & current needs of the Liquid starter are:

400 V 3AC 10 A

Dimensions are Approx. 1600 x 1400 x 2000.

I have read about how they work, but I need to know exactly what is happening.

There are 3 electrodes in liquid starter that they come down. In top position resistance is Max and gradually by coming down resistance decrease. In this phase the current goes to rotor. The rotor begins to turn. When the R(min) is reached the starter short-circuits and the main power will flows to motor (stator).

I don't realize how the rotor V is 1810 when motor is 3300I?

Is rotor begins to turn while the electrodes coming down?

Thanks

I don`t realize how the rotor volts is 1810 when motor is 3300 ?

This is a wound rotor motor . The stator winding is seporate from the rotor. The voltage on the rotor is induced by the stator , the stator and rotor are not in series.

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I don’t realize how the rotor V is 1810 when motor is 3300?

Is rotor begins to turn while the electrodes coming down?

Wound Rotor Motors ...... are like a transformer ..

Consider the Stator to be the primary of the transformer ...

and the Rotor to be the secondary of the transformer

and the turns ratio Np/Ns is 1.8232 : 1

That should help to understand the difference in voltage.

The liquid starter is used to control the load resistance of the

Rotor Circuit which in turn, controls the torque and starting current of the motor in inverse proportion

to the resistance.

The greater the resistance in the rotor circuit, the lower the starting current and the higher the starting torque produced by the motor.

Perhaps the graphic below will further your understanding.

http://jomega.dridoc.com/drives/Images/Typical%20Wound%20Rotor%20Motor%20Characteristics%20with%20Varying%20Resistance.JPG

Kind regards,

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