Preparence of the system to a flight.

Power supply equipment in preparation for the flight is conducted in such embodiments and is switched to the onboard network energysources:

Fig. 7.1

- airport source of AC three-phase current with the voltage 200/115 V and frequency 400 Hz with usage of transformers 36 V;

- airport source of AC three-phase current with the voltage 200/115 V and frequency 400 Hz with usage of rectifiers 27 V and transformers 36 V.

Values of controlled parameters of the power supply system 200/115 В for the steady state mode are represented in the table7.1.

Table 7.1

Values of controlled parameters of СЕП 200/115 V

System of power supply 36 V. The main sources of electricity are two СЕП 36V three-phase transformers TP1 and TP2 with capacity of 2000 VA. Transformers reduce the voltage СЕП 200/115 V to the voltage 36 V.

Emergency power is the three phase static converter ПТС with capacity of 800 VA. The converter is made using semiconductor elements and converts the DC voltage of 27 V to the three-phase alternating current of 36 V with the stabilized frequency of 400 Hz. Functional electrical circuit shown in Fig. 7.2, where АПШ1, АПШ2 are automats of tires switching ПТС is the converter ПТС-800АМ, Тр1, Тр2 are transformers ТС 320СО4А, K1, K2 are contactors.

СЕП 36V is three-phase one with the isolated neutral. The transfer of power from the source to its consumers occurs through two main and one emergency networks, which are located int the distribution device of 36 V (РП36). СЕП 36V is designed for centralized supplying for three-phase alternating electric voltage of 36 V, with the stabilized frequency of 400 Hz. The system includes a source of electricity and power distribution networks.

Fig. 7.2

The system is made so, that in normal mode of operation there are two transformers, while the contactors K1, K2 and K3 are triggered, creating two independent channels of power supply, transformer ПТС does not operate. To provide power for synfazy of the automatic control system (САК), which requires both electrical voltage 200/115 V and 36 V, the transformer Tp1 to be connected to the bus САК, located in the left ЦРП 200/115 V.

The system envisaged two main tires TP1 and TP2 and one tire of emergency. In the case of operation of the main sources of electricity 36V to transformer Tp1 the tire Tp1 and emergency tire are connected, to the transformer Tp2 the tire Tp2 is connected. In case of failure of the transformer Tp1 the automatic switching tires АПШ1 via contactors K1 and K2 performs switching tires Tp1 and emergency tire on the tire working transformer Tp2. In case of refusal of both transformers, switching on the converter ПТС and enable it to emergency tire using contactors K3 and K4 is done automatically.

System of power supply 27 V is designed for centralized power supply DC withvoltage of 27 V. The system includes power sources and electric power distribution network.

Sources of electricity 27 V of the electrical system are two rectifier devices ВП1 and ВП2 that are the main sources and three batteries AK1, AK2, AK3 - emergency sources. Rectifier unit is a unit that consists of a three-phase step-down transformer with two secondary windings, which are connected by two three-phase power rectifiers, electric filters in the primary and secondary circuits and cooling fan driven by three-phase synchronous motor. Rated current ВП is 200 A, with capacity of 6 kW.

Batteries are made from alkaline, nickel-cadmium batteries. The capacity of each battery is 25 Ah. Each rectifier device operates the minimum differential relay (ДМР1 and ДМР2), which provides a connection and protection of ВП.

All tires of thepower distribution network with two channels of power - the main and reserve one, excepting emergency tires of the left and right central switchgear ЦРП 27 in which for the reliability of electricity consumers have three emergency power circuits - the main, reserve and emergency one.

Functional electrical circuit СЕП 27 is shown in Fig. 7.3, where AK1, AK2, AK3 are accumulate batteries 20НКБН-25; ВП1, ВП2 are rectifier devices ВУ-6Б; ДМР1, ДМР2 are minimum differential-relay ДМР-200ВУ; ШРАЖ is the plug airfield power ШРАП-500К; K1 - K14 are contactors.

DC distribution network at operation of both rectifiers forms two independent channels of power. One channel is ВП1 and battery AK1, and the second includes ВП2 and batteries AK2 and AK3. Batteries and rectifiers enabled are parallel and at a load board network, which is already established in magnitude batteries and are only fed. The contactors K1, K2, K4, K13, K14, K7, K8, K9 and K10 operate at the time.

If power breaks in the range of contactors K8 or K9 (break the circle, a short-circuit in the emergency tire left and right ЦРП 27 B) the contactor let their contacts open and switches the emergency power bus left (right) РП 27 B of the emergency bus right (left) ЦРП 27 V. If there is a malfunction in a similar range of contactors K7 or K10, the main bus left (right) AC 27 V supply is switched to the main bus right (left) ЦРП 27 V. In the event of failure of one ВП or short circuit of its feeder ' ДМР it disconnects this ВП from the tire. Simultaneously, the contactor K3 is triggered that connects both channels of power.

Fig. 7.3

If two ВП rejects, the contactors K1, K2, K8 and K9 when you release the contacts and the contactor K3, in their circuit, switch the distribution of network powered by batteries (АБ).

The battery АК1 feeds tire cranes of refueling and external tools. When you switch on the airfield power and press the start button the auxiliary power unit ДСУ is triggered with a contactor K12 and airportsource of electric current is connected to devices of ДСУ start. If running of ДСУ is held by АБ, K11 begins to operate and АБ are switched on to the devices of starting the ДСУ.