Figure 3:Cockpit of PZL W-3A SOKÓŁhelicopter(forreference only)DC power system on the W-3A helicopter is a twochannel system.Each channel is a separate systemthat supplies half(in terms of load)of the power consumers.The power source for the left channel is aGT40PCz8B AC generator working with

　　Figure 3:Cockpit of PZL W-3A SOKÓŁhelicopter(forreference only)DC power system on the W-3A helicopter is a twochannel system.Each channel is a separate systemthat supplies half(in terms of load)of the power consumers.The power source for the left channel is aGT40PCz8B AC generator working with a WU-6Btransformer-rectifier unit.Right channel is powered by a WG-7500 Ja-2s DCgenerator connected to the central bus 2.In addition,an F20/25H1CT2 battery is connected to each channel to recharge and stabilize the voltage under normaloperating conditions.Under emergency conditions(no main power source),the batteries take over thepower supply of the entire DC system.The connection of the two channels occurs automatically whenone of the main power sources or only the batteriesare energized.Central bus bar 1 and 2 supply power to console busbar 1 and 2 respectively,distributing power to the individual helicopter receivers.Power supply to the console bus bars is provided in adouble-track manner via backup fuses built into theleft and right channel DC switchboards.

　　Under possible worst-case conditions,which are notemergency conditions,the maximum current delivered by both DC generators will be 198.2 A.The ACgenerator will deliver 84.3 A at the same time.In special cases where auxiliary equipment is used,the rated current of the WU-6B may be exceeded.The value and time of the overload is within the permissible limits specified by the manufacturer withoutcausing permanent damage.If the WG-7500Ja-2s alternator malfunctions,there isa power deficit during daytime operation in severeweather conditions with the winch running.In severeweather conditions at night there is a power deficitwhen the winch and floodlight are operating.Given the possibility of a short-term overload of therectifier,the power requirement will be provided.When both main power sources are out of operation,all DC mains consumers are supplied from the batterybank.In this case,the operating mode switch must beswitched from normal mode"NORM"to emergencymode"AWAR".Channels are then connected,the central buses ofthe faulty rectifier and generator are disconnectedand the dual power bus consumers are disconnected.The batteries then power only the receivers necessary for a safe 30-minute flight and landing.6.PZL W-3A SOKOL POWER SUPPLY OUTPUTDATAThis chapter presents the basic power parameters ofthe W-3A SOKÓŁhelicopter.It is a modernized version of a helicopter developedin the 1990s,which has been equipped with partiallyupgraded avionics,including a moving map system.

　　The power generation equipment was not changedduring the upgrade.Instead,the battery system waschanged.A BFGoodrich emergency battery wasadded and the Russian battery pack was replacedwith a VENTURA product.The emergency power is provided by the battery tosupply power to the onboard systems in case themain power sources fail during flight.The function ofstarting the engine on the ground,when groundpower systems cannot be used,is taken over by separate battery packs.Table 4 Battery data

NAME MAIN BATTERY EMERGENCY BATTERY Unit Rechargeable battery Rechargeable battery Number ofdevices 21Power rating 13 kW -Voltage 24 V 24 VManufacturer VENTURA AERO BFGoodrich Avionics Systems Model no. F20/25H1CT2 PS-885A Overload capacity --Voltage holding --Capacity 25 Ah 2.5 Ah