Today's Message Index:
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1. 01:11 AM - Alternate Z-32 Heavy duty E-bus feed (Linda Walker)
2. 04:44 AM - Re: Alternate Z-32 Heavy duty E-bus feed (Robert L. Nuckolls, III)
Message 1
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| Subject: | Alternate Z-32 Heavy duty E-bus feed |
=0A=0A=0A=0A=0ASubject: Alternate Z-32 Heavy duty E-bus feed=0A =0A=0ABob.
=0AI wonder if you could comment on the following please:=0A=0AI have notic
ed a 0.7 volt drop across the E-bus normal feedpath diode in a Z-13 (11/01)
architecture.=0AIs this normal and correct?=0A=0AOn reviewing the Z-32 Hea
vy Duty E-Bus Feed diagram, Rev-K-04/20/05, is it in order to alter it to d
o away with the E-bus normal feedpath diode?=0ATo accomplish this, the NC c
ontact of the relay would connect to the Main Bus.=0AThe COM contact would
connect to the E-Bus.=0AThe NO contact would connect to the Main Battery Bu
s and the negative side of the 1N4001 relay diode.=0A=0AIn the relay non-po
wered state, the E-Bus is supplied by the Main Bus.=0A=0AWith the battery c
ontactor open, closing the E-Bus alternate feed switch feeds the E-Bus from
the Main Battery Bus.=0ADo you see any isssues with this arrangement?=0ACo
uld you elaborate on the reasoning behind the E-Bus normal Feedpath diode i
nclusion in Z-32?=0A=0AThank you for your time looking at this.Patrick Elli
ott, G-LGEZ
Message 2
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| Subject: | Re: Alternate Z-32 Heavy duty E-bus feed |
At 03:10 AM 6/22/2013, you wrote:
>Subject: Alternate Z-32 Heavy duty E-bus feed
>
>Bob.
>I wonder if you could comment on the following please:
>
>I have noticed a 0.7 volt drop across the E-bus normal feedpath
>diode in a Z-13 (11/01) architecture.
>Is this normal and correct?
Yes. You can reduced this value slightly by substituting
a Schottky diode . . . but yes, the drop you observe
is normal . . . and insignificant.
>On reviewing the Z-32 Heavy Duty E-Bus Feed diagram, Rev-K-04/20/05,
>is it in order to alter it to do away with the E-bus normal feedpath diode?
>To accomplish this, the NC contact of the relay would connect to the Main Bus.
>The COM contact would connect to the E-Bus.
>The NO contact would connect to the Main Battery Bus and the
>negative side of the 1N4001 relay diode.
This puts BOTH power pathways for the e-but
through a single device. A design goal for
the architecture as published was to craft
independent pathways.
In the relay non-powered state, the E-Bus is supplied by the Main Bus.
>With the battery contactor open, closing the E-Bus alternate feed
>switch feeds the E-Bus from the Main Battery Bus.
>Do you see any isssues with this arrangement?
>Could you elaborate on the reasoning behind the E-Bus normal
>Feedpath diode inclusion in Z-32?
A driver for this goal was gleaned from experiences
with the legacy 'avionics master switch' wherein
all power for the radios comes through one electro-
mechanical device with contacts and moving parts.
This condition has prompted some owners of certified
iron to install a second, back up switch in parallel
with the first.
The as-published architecture eliminates risk
for single failure induced loss of the e-bus.
The voltage drop noted is not significant to
operation of the aircraft. Keep in mind that should
you find yourself without an alternator, the battery
becomes a secondary source of power. Batteries
deliver energy at 12.5 volts and LOWER.
When the alternator is up, the main bus runs at
14.2 to 14.6. The 0.7 volt drop in the normal
feedpath diode supplies the e-bus at 13.5
to 13.9 volts.
If you expect to get full utility from your
e-bus appliances under battery only conditions at
11.0 to 12.5 volts then I suggest that the voltage
drop cited for alternator supported operations
is not significant.
Bob . . .
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