Test on DC Power System

Test on DC Power System

1.Equipment Needed

A 28V ground DC power source and a WQ1 0-40V adjustable voltage stabilizing DC power source.

2.Test on Generators

(1)Preparations.

·Plug in the GPU.

·Start generators.

·Put battery relays 49P(BAT.RLY1)and 50P(BAT.RLY2)at“ON”position,and indicators“BAT.SW1”,“BAT.SW2”,“GEN.1”,“GEN.2”and“BUS.CPL”light up.

(2)Procedure.

·Unplug the GPU.

Note:The GPU can only be unplugged when the rotation speed of the generator reaches the rated value.

·Indicators“BAT.SW1”,“BAT.SW2”and“BUS.CPL”go out.

Generator 1(left):

·Put switch“GEN.1”at“RST”(reset)position and then at“ON”position.Indicator“GEN.1”goes out and indicator“BUS.CPL”lights up.

·Put voltage reading selector 10α at“GEN.1”position and the reading of voltage shall be 28.5V or 27.5V(it depends on the adjustment on the voltage regulator).

Note:If the reading of voltage is not correct,please adjust the voltage regulator.

·Put switch“BAT.RLY1”at“ON”position while switch“BAT.RLY2”remains at“OFF”position.

·Indicators“BAT.SW1”and“BUS.CPL”go out while indicator“BAT.SW2”keeps on.

·After 1s,put switch“BAT.RLY2”at“ON”position.Indicator“BAT.SW2”keeps on while indicator“BUS.CPL”remains off.

·Put switches“BAT.RLY1”and“BAT.RLY2”at“ON”position simultaneously and the corresponding indicators shall go out while indicator“BUS.CPL”lights up.

Generator 2(right):

·Put switch“GEN.1”at“OFF”position and indicator“GEN.1”lights up.

·Put switch“GEN.2”at“RST”position and then at“ON”position.Indicator“GEN.2”goes out and indicator“BUS.CPL”lights up.

·Continue with the test on Generator 2 following the same testing procedures as those for Generator 1.

Test on Shedding System:

·Switch on two generators.

·Check generator voltage with a voltmeter(bus bars PP8 and PP9 are both live).

·Put bus bar shedding switch at“SHED”position and indicator“SHED”on 7α panel lights up.At the same time,power will no longer be supplied to bus bars PP10F(D10-D15)and PP13F(A6-A15)on 4α panel as well as bus bars PP15F(E1-E10)on 5α panel and PP12F(K1-K9)on 2α panel.

Note:Maintainers can also check if the bus bars are really shedded by checking if there is still power supplied to the devices connected to the circuit breakers on the panels.

Engine Shutdown:

·Put switches“BAT.RLY1”and“BAT.RLY2”at“OFF”position and all indicators go out.

·Put bus bar shedding switch at“NORM”position and close the safety cap.

3.Test on Battery and Ground Power Socket System

(1)Preparations.

·Make sure both engines are shut down.

·Put switches“BAT.RLY1”,“BAT.RLY2”,“GEN1”and“GEN2”at“OFF”positions.

·All indicators on 7α panel go out.

·Plug in the GPU.

Note:The GPU plug is always live whether it is plugged in or unplugged.

(2)Procedure.

Test on Ground Power System:

·Put switches“BAT.RLY1”and“BAT.RLY2”at“ON”position.

·Indicators“GEN.1”,“GEN.2”,“BUS.CPL”,“BAT.SW1”and“BAT.SW2”light up.

·Put switch“BAT.RLY1”at“OFF”position while switch“BAT.RLY2”at“ON”position and do it the other way around.

·Indicators“GEN.1”,“GEN.2”,“BUS.CPL”,“BAT.SW1”and“BAT.SW2”keep on.

·Put selector 10α at“EXT”(exterior power)position and check the voltage of GPU on the EPD.

·Put switches“BAT.RLY1”and“BAT.RLY2”at“OFF”position.

·Unplug the GPU.

Test on Battery System:

·Put switches“BAT.RLY1”and“BAT.RLY2”at“ON”position simultaneously.

·Put selector 10α at“BAT”(battery)position and check the voltage of the battery on the EPD.

·Indicators“BAT.SW1”,“BAT.SW2”and“BUS.CPL”are off.

Note:

If switches“BAT.RLY1”and“BAT.RLY1”are not engaged simultaneously,the battery relay switched on later will not be engaged because the shortcircuit protection system will prevent the second battery relay from being engaged as a low voltage has been detected in the corresponding bus bar.Also,the bus bars coupling relay will not be engaged.

During the whole test,battery temperature warning indicator shall not light up.

4.Test on Over-voltage Protection and Reset Circuitry

(1)Over-voltage protection.

·Start engines(it is advised to conduct the test together with the test on engine circuitry).

·As generators work with no load,press the small red button in the center of the radiator of the voltage regulator(28P or 29P)to create an over-voltage circuit.1 second later,the output voltage of the generator rises to about 32.5V.Then the over-voltage protection circuit disconnects the excitation circuits of the voltage regulator and engine.Later the output voltage of the generator drops to below 1V and indicator“GEN.1”(or“GEN.2”)lights up.

·Reset the voltage regulator with switch“GEN.1”or“GEN.2”on 6α panel.And the system voltage will be reset to 28.5V and the generator reverse current protector will be engaged.

(2)Emergency Reset.

·Put switches“BAT.RLY1”and“BAT.RLY2”at“OFF”position.

·Put switches“GEN.1”and“GEN.2”at“OFF”position,then at“ON”position.

·Press“EMERG.RESET”(emergency reset)button.

·The voltage of each generator displayed on an external voltmeter shall increase.

·Put switches“BAT.RLY1”and“BAT.RLY2”at“ON”positions.

·Indicators“GEN.1”,“GEN.2”,“BUS.CPL”,“BAT.SW1”and“BAT.SW2”go out.

5.Test on Ground Power Socket System

·Unplug the battery.

·Connect a 0～40V adjustable DC power source to the binding posts of the helicopter ground power socket.The positive binding posts of the power source are connected to the positive and small binding posts of the ground power socket while the negative binding post of the power source is connected to the negative binding post of the ground power socket.

·Adjust the voltage of the adjustable power source to about DC 28V.

·Put switch“BAT.RLY1”at“ON”position.

·Engage circuit breaker 11P and supply power to the helicopter.An external voltmeter will indicate the voltage of the ground power source.

·Increase the voltage of the adjustable DC power source gradually.

·When the voltage reaches 33±1V,no power will be supplied to the helicopter and the screen of the EPD goes black.

·Adjust the voltage of the adjustable power source back to 28.5V.Still,no power will be supplied to the helicopter.

·Disconnect circuit breaker 11P.

·Reconnect circuit breaker 11P so that power can be resupplied to the helicopter and the EPD will display the voltage of the adjustable power source.

·Disconnect circuit breaker 11P to cut off power from the helicopter and the EPD goes black.

·Put switch“BAT.RLY1”at“OFF”position.

·Set the voltage of the adjustable power source to zero and disconnect it from the ground power socket.

·Reconnect the battery.