Synchronous generators of the ESS5 and GAB series

Synchronous three-phase generators of the ЭСС5 series with a static excitation system and automatic voltage regulation are intended for long-term operation in stationary and mobile electrical installations as a source of three-phase alternating current with a voltage of 230, 400 and 440 V, a frequency of 50 and 80 G with a lagging current) and a shaft rotation frequency of 1000 , 1200, 1500 and 1800 rpm (Table VI.5).

The abbreviated designation of the generator, for example, ЕСС5-61-4У2, is deciphered as follows: ЕСС5 – series; the first number after the dash is the size; the second digit is the length of the stator; chatter digit - the number of poles; U(T)-climatic performance; 2 - accommodation category.

Generators in climatic version U category 2 are produced for intra-Union deliveries and deliveries for export to countries with a temperate climate, and in climatic version T category 2 — for deliveries for export to countries with a tropical climate.

The generators are self-excited through a built-in block of silicon rectifiers, and the initial excitation is from the initial excitation transformer or from a direct current source. The stabilizing device provides automatic maintenance of the voltage within ±5% of the average regulated voltage at all loads (from no-load to the nominal value) and a power factor from 0.8 (lagging) to 1 at the established temperature of the generators and the nominal frequency of rotation.

The generators withstand 10% non-overload (power for 1 hour at the nominal values of voltage and power factor. They allow operation in repeated short-term mode with a duration of inclusion of up to 25% of the total loading time when the load during the working time of the current cycle is up to 125% of the nominal value An unloaded asynchronous motor whose nominal power does not exceed 70% of the generator power is allowed to be started at idle speed, they are not intended for parallel operation.

When reducing the rotation of the generator with the nominal frequency in the idling mode, the residual magnetic flux of the rotor induces a small electromotive force in the main and additional windings of the stator. At the same time, the value

The EMF of the additional winding is 7-15 times less than the EMF of the main winding and is insufficient to open the semiconductor diodes (block of silicon rectifiers) and self-excitation of the generator. Two methods of initial excitation are used: from a direct current source (Fig. VI.3) and from the TUB initial excitation transformer (Fig. VI.4).

In the presence of a source of direct current B (Fig. VI.3) with a voltage of 12-24 (battery), the generator is excited by a short-term (0.5-1.5 s) supply of voltage to the winding of the OP rotor through contact rings. For this purpose, a button with normally open contacts and a limiting resistance /?, the value of which is determined by the source voltage, are provided.

To excite the generator by the second method (Fig. VI.4), the EMF of the main winding 00, which consists of the EMF of the additional winding OD, is supplied to the block of silicon rectifiers BKV through the initial excitation transformer TNV (within 1-3 s). At the same time, the three-phase excitation circuit from the compounding transformers of the BCTS and resistances of the SC to the rheostat of the RU installation (for generators of the 8th and 9th dimensions) or from the additional winding of the OD to the compounding choke of the DRK (for the generators of the 6th dimension) is opened. The latter has self-return and is made with one closing and two opening contacts. When supplying the EMF of the main winding 00 through the PV switch, TNV transformer and additional OD winding to the block of silicon rectifiers BKV, the generator is excited to 20% (for generators of the 8th and 9th sizes) or to 40% (for generators of the G-ro size) nominal voltage, the EMF of the additional winding becomes sufficient to open semiconductor diodes.

Since the TNV is designed for short-term operation, as soon as the generator voltage is established, the PV handle is released, at the same time the transformer circuit is closed - the rheostat of the installation for generators of the 8th and 9th dimensions and the additional winding - the compounding throttle of the dimension and the primary winding is opened TNO

 

 

 

 

Fig. VI.3. Electrical scheme of generators with initial excitation of a direct current source.

 

 

 

 

Fig. VI.4. Electrical diagram of generators with initial excitation from a transformer (TIIB)
The designations are the same as in fig. VI.3.

 

 

 

 

The rheostat of the switchgear installed in the scheme is designed to set the desired generator voltage within 95-100% of the nominal value. When the load is connected to the clamps of the machine, a current flows through the main winding of the stator, which creates a force in the generator that magnetizes the rotor winding directed against the force. To compensate for the action of the demagnetizing stator magnetic flux and to maintain the generator voltage at the set value, the rotor winding current must be increased. When the power factor changes, the load current of the rotor winding is automatically changed with the help of a stabilizing device. The latter in generators of the 8th and 9th dimensions consists of compounding transformers and resistors, and in generators of the 6th dimension - from a three-phase choke that compounds with an air gap.

The scheme for connecting the phases of the windings of compounding transformers to the circuit of the additional winding and the compounding choke to the purpose of the main and additional windings of the stator is arranged in such a way as to ensure the necessary nature of the change in the rotor winding current when the load changes both in magnitude and in phase (coscp) in order to maintain a constant voltage of the generator with an accuracy of ±5% of the average regulated value.

Schematic diagrams of control panels for generators of the 6th dimension are shown in fig. VI.5. The energy produced by the generator 11 is fed through the measuring current transformers 6 and the automatic switch, which serves to protect the generator from overloads and short circuits, to the clamps for connecting the load.

Schematic diagrams of control panels with a stabilizing device for generators of the 8th and 9th dimensions are shown in fig. VI.6. The energy produced by the generator 11, through the stabilizing device 10, measuring current transformers and automatic switch 1, is supplied to the buses of consumer lines. Lines No. 1 and No. 2 are protected from overloads by automatic switches 12 with thermal disconnectors. Protection of the generator from overloads and short circuits of the line is carried out by circuit breaker 1 with a combined disconnector, which can be used as line No. 3 to connect the load to the full power of the generator. The operating mode of the generators is controlled by measuring devices.

 

 

 

 

 

Fig. VI.5. Schematic electrical diagram of the control board for the generator of the 6th size with initial excitation:
a - from the battery; b - from the transformer of initial excitation;

1 - automatic switch; 2 - voltmeter; 3 - frequency meter; 4 - ammeter; 5 - switch; 6 - measuring current transformer; 7 - setting rheostat; 8 - resistance (transformer); 9 - switch; 10 - stabilizing device; 11 - generator.

 

 

 

 

Alternating current generators of the GAB series

These generators are manufactured with a voltage of 127 and 230 V. The designs of these generators on axial nodes have a lot in common. The control unit contains active compounding resistances or transformers. These elements are an integral part of generators, and in some places they are structurally connected with them, and in others they are in a separate unit of equipment.

The technical characteristics of the generators are given in the table. VI.6. Alternating current generators of the GAB series are divided into two groups - normal frequency 50 Hz and increased frequency 400 Hz.

 

 

 

 

Fig. VI.6. Schematic electrical diagram of the control panel for generators of the 8th and 9th dimensions with initial excitation. VI.5.

 

 

 

Most often, such generators are used in stationary and mobile power plants of geological exploration organizations - they are generators of small and medium power. The principle of their operation does not differ from the generators of thermal and hydroelectric power stations, but the specifics of their use determined a number of features in the design and electrical circuit. The generators of these power plants include elements of automatic voltage regulation in their design, in addition, they can produce electricity both without transformation and with voltage transformation.