Product Series

STC Series 3-phase AC Synchronal Generator

　　This product is widely used in industries, mines, communications, post and telecommunications, high buildings, ship-building and field constructions as a main or auxiliary power supply.
This series generator adopts the 3-phase star connective method with neutral point. The line voltage is 400V, phase voltage 230V, frequency 50Hz, Power factor 0.8 (delay). According to the needs of users, we also may provide other generators with 60Hz and other voltages.
This series generator links directly or through V belt with the prime mover. The generator can rotate at both positive and negative directions, and continuously operate at the rating conditions.
In order to make the generator operate normally, you must read this manual carefully before use it.

I. Specification and Performance

　　This series generator adopts harmonic excitation. Besides the main windings on the stator core, a set of harmonic windings is equipped, which is connected to the windings in the magnetic field through a 3-phase or single-phase bridge rectifier, to excite. Due to the third harmonic wave voltage will go up correspondingly when generator has load, the self-exciting constant voltage property can be reached without any complex automatic voltage regulator.

Main technical parameters of generator:

　　Note: The rotating speed of the generator with 60Hz is 1800 rpm.
This series generator has excellent dynamic characteristics; it can directly under non-load start the incompatible asynchronous cage motor without adding any device.

II. Application Environment

　　This series generator is applicable to the following environments;
1. Attitude is not higher than 1000m.
2. Ambient temperature is not more than +40℃.
3. Relative humidity is not more than 85%.
4. Work field without conductive dust and corrosion gas destroying metal insulation.
5. Work field without explosion risk.
When the ambient temperature is more than +40℃ or the attitude is higher than 1000m, the output power of the generator shall correspondingly drop down according to the technical standard.

III. Structure

　　This series generator adopts the rotating field type. The stator core consists of 0.5 mm high quality laminated silicon sheet; the core of magnetic pole consists of 1mm electric laminated steel plate. The wire adopts the high strength enamel insulated wire. The isolative grade of stator is H grade, while the isolative grade of rotator is B grade. The generator with power 3KW-24KW is 3-phase third harmony wave. The switch box of generator is located on the top of base; the connecting board, silicon rectifier elements, 6.3V indicator and voltage meter are installed in the box. The output cables are leaded out from the connective board through the outlet hole at the back of the box, when connecting, you must pierce through the seal film on the wire outlet hole plate with a small knife. The wiring principle of the generator is shown in Figure 1. In the Figure 1, z4, z5 as well z6, z7 are the harmony wave coils of secondary windings with various number of turns. They can reach the aim to adjust the non-load voltage through changing the positive or negative series connection of the connecting terminals. When z4 connects to z6 and z7 connects to z8, this is the situation that the both basic wave coils are be used independently. When the generator delivers, the connecting terminals have been adjusted; the user may change the connection of the basic wave coils according to own need. The generator with power 30KW-150KW is the single-phase third harmony wave. The terminal box of the generator is equipped with AVR automatic voltage regulator and silicon rectifier elements. The wiring of the generator is shown in Figure 2.

　Main electric elements table of generator configuration:

IV. Notices before use
1. Connecting the output cable to the connecting board in the switch box of the generator. The cable shall have sufficient section area to ensure safe power transmission.
2. Open the rear cover of the machine shell; check whether the electric brushes are normal.
3. Each output terminal shall be equipped with a switch and an appropriate capacity fuser. Before the generator starts, any switch at output terminals shall be at the open position.

V. Start and Stop

　　1. Start;
(1) Adjusting the magnetic field varistor on the switchboard to the short position, that is turning to the highest position of the voltage indicated by the arrow.
(2) Start the prime mover. When the rotating speed nears to the rating, the generator will be able to establish the voltage through excitation. Adjusting the rotating speed to a rotating speed that is a little higher than the rating to compensate the drop-out of the rotating speed when full load. At the same time adjust the magnetic field varistor until the indication of the voltage meter reaches 400V.
(3) Close the switches at the output terminals; the normal power supply may be achieved.

　　2. Stop
(1) Remove the loads at the output terminals and turn off the switches.
(2) Stop the prime mover.
(3) Adjust the magnetic field varistor to the short position.

　　3. Notices:
(1) Avoid the short circuit of the output terminals of the generator, because the short circuit may damage the rectifier elements.
(2) The loads shall be removed before stop. If stop with load, the residual magnetism may be lost. When use nest time, you must re-magnetize.
(3) After stop, adjust the magnetic field varistor to the short position to avoid the difficulty of establishing voltage when start next time.

VI. Maintenance, Check and Repair

1. General maintenance
(1) Protecting the generator from wetting. When store, it shall be placed at the dry position. When place on the earth or concrete floor, you must put woods under it. When store, you must cover it with oilskin to avoid the entering of wet.
(2) Avoid any intrusion of dirt, water, metal scrap or other foreign material when store or in running.
(3) No article is allowed to cover on the generator. So doing will prevent the heat from dissipation to cause the generator overheat damage.
(4) Pay attention to the ventilation and overheat of generator, the indications of current and voltage. Avoid overload.
(5) Often check the abnormal spark on the bus rings. If find the abnormal noise when running you shall immediately check.
(6) Where moisture and dust are too much or containing flammable gas the generator shall be not used.
(7) After 1000-1500 hours of operation, the grease in the ball or roller bearings shall be changed, at least they shall be changed two times each year. The adding grease quantity shall be the 2/3 of bearing cover, too much is not allowed. The adding grease tools shall be clean and the hybrid use is not allowed for different greases. The recommended lubricant grease is No. 3 lithium grease. The temperatures of the ball or roller bearings shall be not higher than 55℃.
(8) The silicon rectifier elements shall be held ventilation well; on the radiator and shell no article that prevent heat from dissipation is allowed to cover.
(9) Often clean the dirt on the silicon rectifier elements and check the fastened screws on the silicon rectifier elements for loose.
(10) Check the connecting terminals in the control penal for sealing off, broken ends or loose.

2. Check and Repair
In order to ensure the safe running of the generator, and find and eliminate the potential accident cause, the regular check is necessary for the generator. Generally make a check each three months, an overhaul each year.

　　(1) Common check and repair items
① Remove the window cover and clean dust and dirt in the generator. The better cleaning method is using the compression air, whose pressure is not higher than 2 atm., to blow.
② Clean the surface of bus ring. First using the coarse cloth (the cotton goods without cotton wools and fabrics) dipping with some kerosene rub the surface, then using the clean coarse cloth rub it until dry.
③ Remove the bearing cover and check the lubricant grease, if find uneven color, change it.
④ Check the carbon brush for wearing and adjust the pressure of spring, change the worn carbon brush.

　　(2) Overhaul items
① Use a 500V megohmmeter to measure the insulated resistance. If the resistance to ground is less than 1 MΩ, the drying shall be done.
② If the surface of bus ring has become rough or worn, we shall recover its smooth through machining and turning cutting.
③ Remove the ball or roller bearings and clean them with kerosene; their turning shall be flexible and no noise. Add some grease and re-assemble.
④ Check the contact situation of wiring parts and fasten the wiring nuts.
⑤ Clean the internal part of the generator throughout with blowing air, especially the bus ring and the joint.

　　(3) Notices when check and repair
① Removed parts shall be stored in a container to avoid any lose due to random place.
② Main parts such as rotator, end cover, machine base, bus ring, carbon brush etc. must be placed carefully to avoid any damage due to impact.
③ The removed connecting terminals shall be marked to avoid incorrect connection when re-wiring.
④ The removed bearing and cover shall be covered with clean paper to avoid the intrusion of dirt. If find dirt, you must change all the greases.
⑤ The arcs between the carbon brush and the bus ring shall fit, otherwise shall re-polish.
⑥ After finish assembly of generator, using hand rotate the rotator, check noise and flexible.
⑦ The screws on the end covers and the magnetic poles must be fastened in a diagonal crisscross method.

3. Troubleshooting

Installation Size STC3KW∽50KW

Table I

Installation Size STC64KW∽150KW



Table II