Post by LOU on Nov 3rd, 2010 at 1:45am
Mark wrote...
I'm with CoolP on the External Power light. When External Power is OFF the light still looks like it is ON. Looking at the images that he has shown in his post, you can see a difference in the brightness between ON and OFF, although it does look like the light bulb is glowing. It is much clearer when you get in close like in the images, not as noticeable from further away.
The neon light only shows that the EP (external power) plug is connected. BOTH METERS & ESSENTAIL SELECTORS ARE SELECTED TO EP!
Before closing (ON) the EP switch you must check the volts & freqs.
Selecting the switch to ON or ground service connects the EP to the aircraft busses. You then select Essential power to external to power all the busses.
Here you see the external power is plugged in but the switch is off and both the meter selector [lower] and essential power selector are selected to external power, yet the meter [lower] is showing nothing. This is not correct for the meter selector- the meter selector should show something! The essential power should show nothing as it is indeed not powered - hence the red light for failure.
You must be able to select the meter switch to the external source to check it's volts and freqs before powering the aircraft. The meters should show volts & freqs (~120volts & ~400 cycles). I went over to the 707 and it's the same problem.
The external switch is a magnetic switch which has logic. The logic is that no two sources can power the plane at the same time. If EP is selected and you start an engine and close the generator switch (MGR main generator relay) the EP trips. If you close the AGR (aux generator relay - APU) the external switch trips or the engine trips, which ever is powering the aircraft. Same on the 707.
NOTE: I am not able to get the external switch to stay up (ON). I get it to snap up, but it returns to off and will not stay engaged. Huummmmmm?????
I'm with CoolP on the External Power light. When External Power is OFF the light still looks like it is ON. Looking at the images that he has shown in his post, you can see a difference in the brightness between ON and OFF, although it does look like the light bulb is glowing. It is much clearer when you get in close like in the images, not as noticeable from further away.
The neon light only shows that the EP (external power) plug is connected. BOTH METERS & ESSENTAIL SELECTORS ARE SELECTED TO EP!
Before closing (ON) the EP switch you must check the volts & freqs.
Selecting the switch to ON or ground service connects the EP to the aircraft busses. You then select Essential power to external to power all the busses.
Here you see the external power is plugged in but the switch is off and both the meter selector [lower] and essential power selector are selected to external power, yet the meter [lower] is showing nothing. This is not correct for the meter selector- the meter selector should show something! The essential power should show nothing as it is indeed not powered - hence the red light for failure.
You must be able to select the meter switch to the external source to check it's volts and freqs before powering the aircraft. The meters should show volts & freqs (~120volts & ~400 cycles). I went over to the 707 and it's the same problem.
The external switch is a magnetic switch which has logic. The logic is that no two sources can power the plane at the same time. If EP is selected and you start an engine and close the generator switch (MGR main generator relay) the EP trips. If you close the AGR (aux generator relay - APU) the external switch trips or the engine trips, which ever is powering the aircraft. Same on the 707.
NOTE: I am not able to get the external switch to stay up (ON). I get it to snap up, but it returns to off and will not stay engaged. Huummmmmm?????