Overview

 

Frequency quick rheostat is a kind by cast-iron piece or armor plate folds core, cover again outside on the three-phase reactor of winding, in receiving the circuit in rotor winding, the equivalent impedance of the decision of its winding reactance and core loss changes as the frequency of rotor electric current.

 

Begin from 60 time, use what frequency quick rheostat will replace starting resistor to circle electromotor of line rotor asynchronous in order to control extensively to start. Frequency quick rheostat is a kind do not have contact electromagnetism component still, use it to frequency change sensitive and automatically block. Frequency quick rheostat is the three-phase reactor with an iron very big damage essentially, its structure is similar to the three-phase transformer that does not have winding 2 times.

 

Frequency quick rheostat is a kind those who have unique structure is new-style without contact component. Its are exterior structure and three-phase reactor likeness, have 3 core column and 3 winding composition namely, 3 winding receive astral form, connect through winding of slip ring and brush and rotor of three-phase of electromotor of the type that wind a string.

 

When electromotor of the type that wind a string just began to start, electromotor rotate speed is very low, f2 of reason rotor frequency is very big (be close to F1) , the loss in core is very big, namely equivalence resistor Rm is very big, reason restricted the electric current that start, increased to start torsion. As the addition of N, frequency of rotor electric current drops (F2=s F1) , rm is reduced, make the electric current that start and torsion hold fair numerical value. The flowing variation that frequency quick rheostat uses rotor frequency F2 actually is achieved make rotor loop total resistor flowing reduced goal. After the end that start, rotor winding is short receive, frequency quick rheostat is excised from inside circuit. Because Rm mixes the equivalence resistor of frequency quick rheostat to reactance Xm follows frequency of rotor electric current and change, reaction delicacy, reason calls frequency quick rheostat.

 

Working principle

 

Frequency quick rheostat is a special three-phase core reactor actually, it has core of a 3 column, there is a winding on every column, three-phase winding receives astral form commonly. The impedance of frequency quick rheostat has apparent metabolic electricity as the change of voltaic frequency when frequency is tall, impedance cost is high also, when voltaic frequency is low, impedance cost is low also. This one frequency of frequency quick rheostat is very characteristic agree with the starting process that controls asynchronous electromotor. When starting, fz of frequency of rotor electric current is the biggest. Rf and Xd are the biggest, electromotor can obtain bigger starting torsion. After starting, as rotate speed raise frequency of rotor electric current to be reduced gradually, rf and Xf are reduced automatically, so electromotor can get constant torsion character approximately, the stepless that realized electromotor is started. Start after ending, frequency quick rheostat should short circuit excision.

 

Action

 

Frequency quick rheostat is one kind does not have contact electromagnetism component, be equivalent to an equivalence impedance. In electromotor starting process, in starting electric current along with rotor as a result of equivalence impedance reduce and drop automatically of high frequency composition to change automatically in order to achieve block, need to use one class rheostat only thereby, can start motor smoothly rise.

 

Rheostat is the three-phase reactor with very big loss of a core essentially. It reachs coil by the core that becomes with superposition of several E armor plate two bodies composition. The clip between armor plate with washerbed down the livestock, maintain a span to leave, come loose with benefit hot.

 

When electromotor of the type that wind a string just began to start, electromotor rotate speed is very low, f2 of reason rotor frequency is very big (be close to F1) , the loss in core is very big, namely equivalence resistor Rm is very big, reason restricted the electric current that start, increased to start torsion. As the addition of N, frequency of rotor electric current drops (F2=s F1) , rm is reduced, make the electric current that start and torsion hold fair numerical value. The flowing variation that frequency quick rheostat uses rotor frequency F2 actually is achieved make rotor loop total resistor flowing reduced goal. After the end that start, rotor winding is short receive, frequency quick rheostat is excised from inside circuit. Because Rm mixes the equivalence resistor of frequency quick rheostat to reactance Xm follows frequency of rotor electric current and change, reaction delicacy, reason calls frequency quick rheostat.

 

Put in the problem

 

The wiring when frequency quick rheostat leaves factory receives the 90% take a percentage of a deal of online circle to go up, if electromotor is received,go up after rheostat is started, have one of following cases, can undertake adjustment according to undermentioned method:

 

1.The electric current that start is too big (be more than 2.5 times) , start too fast, can try to increase a number, receive take a percentage of a deal 100% rounds number, its effect makes the electric current that start is reduced, the moment of force that start is reduced at the same time.

 

2.The electric current that start is too small (be less than 2 times) the moment of force that start is insufficient, start too slow, can try to reduce a number, receive take a percentage of a deal 80% rounds number, its effect makes the electric current that start increases, the moment of force that start increases at the same time.

 

3.If machinery is in,stop machine start afresh after period of time, because machinery is laden especially heavy, start again when having difficulty, can move electromotor point several times, after making machinery rotational a few times, can use normally.

 

Actor defect

 

Advantage: The structure is simpler, cost is inferior, safeguard convenient, flowing start.

 

Defect: Inductance exists, cosΦ is inferior, the torsion that start not very big, comfortable start at circling line type electromotor to carry gently.