JPS6023595B2 - Similar direct-on-line starting method for motors using an alternator as a power source - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a similar direct-on starting method for electric motors using an alternating current generator as a power source.

When starting an electric motor using an engine generator or the like as a power source, the capacity of the engine generator is determined by the starting capacity of the electric motor.

Generally, the engine generator capacity (ACG) is the following '1
- Expressed by the formula. ACG; two poisonous three Xd'pm - two shore three
E is the generator voltage drop at the time of starting, xd' is the starting transient reactance of the generator, pm is the motor starting capacity, 8 is the multiple by the motor starting class, c is the starting coefficient of the starter, and p is the motor capacity.

When the load driven by the electric motor is light, the starting torque of the electric motor may be small. Therefore, low-voltage starting is performed using a Y-Δ starter or a starting compensator, etc. to achieve the above tl'.
Reduce the motor starting capacity pm in the equation, and reduce the generator capacity ACG
However, when starting motors for opening and closing water gates, motors for raising and lowering elevators, etc. that require heavy-load starting using an engine generator as a power source, low-voltage starting methods cannot be used. Therefore, direct starting, that is, direct starting with the motor rated voltage unchanged, is performed. Therefore, the capacity of the engine generator needs to be 5 to 7 times larger than the capacity of the electric motor, which is extremely expensive and uneconomical.

The purpose of the present invention is to improve the problems of the prior art. Approximately 70% of the voltage is applied to the motor to reduce the voltage drop in the generator at the time of starting, and the motor starting current at that time saturates the generator magnetic circuit, preventing the circuit from being cut off at the next moment. Perform direct voltage starting.

In this way, the motor starting coefficient c in equation '1}
In the above case, 047 = 0.49, and ``Even if we ignore the effect of the generator's magnetic circuit saturation,'' the generator has a capacity of 49% of the generator capacity by the conventional direct-on-line starting method (c = 1). This makes it possible to start the generator, and the effect of the generator's magnetic circuit saturation is actually amplified, making it possible to use a smaller capacity generator.Examples of the present invention will be described below with reference to the accompanying drawings. explain.

FIG. 1 is a wiring diagram showing three-phase components of a similar direct-on-line starter for carrying out the present invention, and FIG. 2 is a similar structural diagram. In these diagrams, there is a bypass Shijiro 2 in the middle of Kamesama.
``n, and n2'' are the main circuit windings respectively wound around the sectional windings divided by the bypass magnetic path 2, and n and ' are the sectional magnetic paths around which the main circuit winding n is wound. It is assumed that the compensating winding is wound in the direction n and has approximately equal ampere turns. The ratio is a winding wound around the bypass magnetic path to prevent leakage magnetic flux. Main circuit winding n
, and the neutral point are connected to the neutral point via the power switch S, and the neutral point switch S3, and the motor M is connected to the main circuit winding n, and the midpoint of the gunwale. This embodiment is also for low voltage use, and in this case the compensating windings n, F are connected in parallel with the main circuit windings n, via a switch S2. S4 is an opening/closing switch for the winding n3 for preventing leakage magnetic flux.In the above configuration, when the power switch S and the neutral point switch S3 are opened, the electric motor M receives EM, =
EX-sei-......■n, a voltage of 10 broadsides is applied, the motor current fM at that time is, and the power supply current ls is IS:IMXn. Sky Buddha: IDXn. Sky n2Xn. Kin2
=IDX (this Air Force) 2 ---...---{41.

(Tabushi 1 indicates the power supply current at direct startup). Therefore, now Kou=o. 70% of the 7th rib E pressure key power supply voltage E
If the voltage is ``At this time, the starting current flowing into the power supply l''
s is from the above formula {4}・S:・DX (city craft) 2=1
0x0-〆=0-4gD, and "instantaneous initial starting current of 49% of the current lo that flows during direct starting flows into the power supply.

In this way, in the case of the above example, in the present invention, the magnetic circuit of the generator is saturated by the initial starting current of 49% at the time of direct starting. At the same time, since the initial starting capacity of the motor is 49%, the voltage drop at the time of starting the generator is reduced accordingly, and the generator capacity can be even smaller.

In other words, the generator capacity is 49% compared to the direct start method.
The following small capacity ones are sufficient. After a time of about 15 to 20 Hz, when the switch S2 is closed and the main circuit winding n is made into a non-inductive coil by the orange wire winding n,', 100% voltage, which is the same as the power supply voltage E, is applied to the motor M. Direct start.

After the rotation of the motor increases due to this direct start, the neutral point switch S3 is opened and the operation switch is closed to enter the operating state.

Winding n3 is set at the "initial stage of startup, that is, main circuit winding n,
- is working effectively, even if the bypass magnetic path 2 is for preventing magnetic flux leakage, the power switch S,
and neutral point switch S3 are closed, switch S4
omit.

Further, in the starting state, that is, when the switch S2 is closed and only the main circuit winding is operating, the switch S4 is closed to allow the magnetic flux to pass through the bypass feed path 2. Table 1 is a comparison table of the terminal voltage drop of the engine generator between the conventional direct-on-line starting method and the similar direct-on-line starting method according to the present invention.

Table 1 Table 1 shows actual measured values when an ACO=20KVA engine generator is used as a power source and the motor starting class is F class.

As is clear from Table 1, the allowable voltage drop during starting using a 20KVA engine generator ΔE=o. In the case of 2, the conventional direct start method does not work. It was only possible to start up to the electric motor of Fox W, but according to the present invention, 7. It is possible to start even the electric motor with a spot W.

If you look at this from a different perspective, it is the same 2. to start a motor with W, but with the direct starting method of the secondary
However, according to the present invention, a generator with a capacity of 2V/5-9VA is sufficient to start the process.

That is, the same 2. It is shown that in the similar direct-on-line starting method of the present invention, which uses exactly the same starting voltage drop conditions as in the case of direct-on-starting a motor with a power of W, the generator capacity can be approximately 1/3 of the capacity. The embodiments shown in FIGS. 1 and 2 are examples in which the bypass is provided with a winding for preventing magnetic flux leakage, but as shown in FIG. 3, the winding for preventing magnetic flux leakage may be omitted. You can also do it. That is, if the windings of the main circuit windings n, , n2 in Fig. 1 are taken as t2, then the E river = EXt point in Fig. 1......■ The winding of the main circuit windings n, , n2 in Fig. 3 is After the number,
t2, in Figure 3 E heart iEX; wool
......To make '61EM=EMゞ, t2 - Qt2 10 t2 1' + t2 .・Q=Taigu Q<1, (t,+ra)〉(t,'10t2)=ra'
It turns out that it is sufficient to set <t.

That is, in the case of the embodiment shown in FIG. 3, by taking into account the coil leakage magnetic flux and setting t'<t, a simple structure can be obtained in which the winding ratio shown in FIGS. 1 and 2 is omitted. I can do it. FIG. 4 shows another embodiment in which the present invention is applied when the distance L from the engine generator that is the power source to the electric motor M is extremely long. The terminal c of the circuit winding and the terminal c2 of the extension winding can be selected, and the terminal c of the extension winding can be selected.
By selecting option 2 and starting, a voltage higher than the power supply voltage E is supplied to compensate for the voltage drop in the electric line at the time of starting.

The other configurations are the same as those shown in FIGS. 1 and 2. The embodiments shown in FIGS. 1 to 4 are examples in which the present invention is applied to low pressure applications, but in the case of high pressure applications, the embodiments are as shown in FIGS. 5 to 7.

That is, in FIGS. 5 to 7, the compensation hakama line n,
' is separated from the main circuit, high voltage switches are used only for switches S, S3 and S5, and low voltage switches are used for switches S2 and S4. Note that FIG. 5 corresponds to the embodiment shown in FIGS. 1 and 2, FIG. 6 corresponds to the embodiment shown in FIG. 3, and FIG. 7 corresponds to the embodiment shown in FIG. It will be obvious without further explanation that these embodiments correspond to the embodiments shown in FIG. As described above, according to the present invention, for example, when the voltage applied to the motor instantaneously at initial startup is 70%, 0.
7 = 0.43, which means that the starting capacity can be approximately half of the starting capacity during direct starting, and furthermore, during this short period of time during initial starting, this halved load current reduces the magnetic circuit of the generator. By saturating, the voltage drop when switching to the next direct start is significantly reduced, and these two factors combine to make it possible to start the motor using a small-capacity generator, which was previously impossible to start. Furthermore, it has the great effect of making it possible to start a large-capacity motor, which was impossible with a conventional generator, of the same capacity.

[Brief explanation of the drawing]

The attached drawings show a starter for realizing the similar direct-on-line starting method of the present invention, and FIG. 1 is a wiring diagram showing the first embodiment, FIG. 2 is a structural diagram of FIG. 1, and FIG. 4 is a wiring diagram showing a second embodiment, FIG. 4 is a wiring diagram showing another embodiment, and FIGS. 5 to 7 are wiring diagrams showing examples in which each of the above embodiments is applied to high voltage applications. All of them indicate one phase of the three phases. 1...Open magnetic path, 2...Bypass magnetic path, n,
, n2...main circuit winding, n. ...Compensation winding, ratio...
...magnetic flux leakage prevention winding, S,, S2, S3, S4,
S5...Switch. Figure l Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] 1. A main circuit winding divided into two or more sections is applied to a closed magnetic path having a bypass magnetic path, and one sectioned magnetic path passing through the bypass magnetic path is wound around the sectioned magnetic path. Using a starter equipped with a compensating winding having approximately the same ampere turns in the opposite direction to the main circuit winding on the power supply side, immediately before direct starting, the motor is connected to the midpoint of the main circuit winding. A reduced voltage is applied for a short time to reduce the voltage drop of the generator at the time of starting, and the magnetic circuit of the generator is saturated, and then the compensation winding is closed and the main circuit winding on the power supply side wound around the segmented magnetic path is A similar direct-on-line starting method for a motor using an alternating current generator as a power source, characterized in that the motor is started directly on-line using a non-inductive winding. 2. A patent claim in which a winding for preventing magnetic flux leakage is applied to the bypass magnetic path, and the winding circuit for preventing magnetic flux leakage is closed while a reduced voltage is applied to the motor by the main circuit winding to prevent magnetic flux leakage to the bypass magnetic path. A similar direct-on-line starting method for an electric motor using an alternating current generator as a power source as described in Scope 1.