Today's Message Index:
----------------------
1. 07:35 AM - Re: Relay vs Continuous Duty Contactor (Robert L. Nuckolls, III)
2. 08:05 AM - Re: Relay vs Continuous Duty Contactor (tx_jayhawk)
3. 08:06 AM - IVOPROP (Robert L. Nuckolls, III)
4. 08:14 AM - Re: Re: Relay vs Continuous Duty Contactor (Robert L. Nuckolls, III)
5. 09:43 AM - Re: IVOPROP (Jim Corner)
6. 11:33 AM - Re: IVOPROP (Robert L. Nuckolls, III)
7. 12:02 PM - E-Bus Alt Feed wire size (dbuds2)
8. 01:36 PM - Ford alternator (Roger Cole)
Message 1
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| Subject: | Re: Relay vs Continuous Duty Contactor |
At 12:19 AM 4/10/2009, you wrote:
>
>All,
>
>In comparing the continuous contactor (S701-1) to the relay
>(S704-1), I assume that the reason people choose the relay is due to
>the lower coil current draw? Drawback is obviously that it is
>limited to 20 amp. Should the 20 amp limitation be based on the max
>continuous or max intermittent current draw of items connected to
>the relay? Also, in looking at some other 12V coil units, they
>listed the max continuous voltage at 13.2 volts. I assume that is
>not a concern with the S704-1?
You don't say how you intend to use the relay
or contactor you're searching for.
Your 'comparison' of the two devices cited reveals
that they are entirely different breeds of cat. One
can buy relays/contactors rated at milliamps to tens of
thousands of amps. Further, they'll be offered in
a constellation of coil or control voltages and
currents. Finally, they may be tailored to specific
tasks that present unusual problems for meeting
design goals.
Ratings for contactors, switches and relays are
driven mostly by SWITCHING loads. This is a dynamic
thing that can be all over the map depending on
voltage level, AC vs. DC, and how the load's
characteristics affect what's going on during
contact closure and opening events.
But comparing published ratings of the various
devices is fraught with intellectual potholes.
One manufacturer's ratings may cite some level
of pass-fail, post-test performance after
10,000 cycles while others shoot for the moon
. . . say 500,000 cycles.
In your OBAM aircraft, you are unlikely to put
1,000 pilot-operated cycles on any power relay or
contactor over the time you own the airplane.
If you're designing with failure tolerance in
mind, then $time$ expended pouring over spec
sheets with some notion of improving on the
service life of the device is probably not
going yield a positive return on your expenditure.
So now that we've expanded the universe of
parts from which you might select a suitable
device, what is the application for which you're
seeking a relay or contactor?
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 2
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| Subject: | Re: Relay vs Continuous Duty Contactor |
It is for various reasons...possibly an essential bus alternate feed (14 amp continuous,
23 max intermittent) or for a separate dedicated avionics bus that powers
redundant avionics equipment with similar bus loads (no worries..."essential"
avionics are not switched). I know my essential load and architecture may
differ from other people's objective, but I'm good with it.
Question is this...for that type of rating (14 amp continuous, 24 max intermittent)
for something that is going to be switched on and left on the the flight,
what is the preferred contactor/relay?
1) S701 (don't like the hefty current draw).
2) S704
3) A similar automotive relay. Any reason why something like the below wouldn't
work just fine?
http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=171460&
Oreilly's has these for $5.
Thanks,
Scott
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=238616#238616
Message 3
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Ron: When the system is not being used it is 3 amp.
BN: What is drawing current when the prop pitch motor
is not running?
Ron: This is a good questions but I do not have an answer for it.
3 x 8 = 24 amp when the circuit breaks. Reaches the stop at 15 amp.
BN: I'm still trying to understand the amount of
energy required to satisfy in-flight operating
requirements. It would stand to reason that
normal running currents (motor in motion and
free of the mechanical stops) are a small
fraction of stall current (motor energized
but prevented of motion because it is
jammed).
Hmmmm . . . I take it you are not the designer
for this product's electrics. Can I have some
conversation with the designer or at least someone
who has understanding of the physics of this
system?
I'm thinking there are easy things you can do
electronically to improve on the system's
integrity and eliminate installation variability/
error to achieve advertised performance.
Ron: I found the system is using 3 amps when there is no load on the spool.
This is when it goes through neutral transition between positive pitch
and negative pitch from neutral. When the switch is not used there is no
current.
The designer has moved to a remote secluded location where he can
work on other inventions without any distractions. That is why I
am doing my best to answer your questions without bothering him.
There are no plans to change or modify our propeller design at this time.
-----------------------------------
Okay, based on this limited exchange I have to deduce
that the gentleman has but a rudimentary knowledge
of how the product works. He is unable to discuss
the physics of the motor's performance at or near
stall with any notions of improving on user-
friendliness. One noteworthy design goal would be
to eliminate the requirement for fine tuning the
resistance in hookup wire and/or sizing a specific
style of breaker. This feature alone would get
him tossed out of a design review meeting at
any of the places I've worked.
My best guess is that the motor draws 3A at
the "no-load" point roughly centered on min-
max prop pitch. Departures either direction
from neutral winds up the springs causing motor
current to rise. Peak current happens at
some point just before the system hits the
mechanical stops. There is no current draw
when the motor is not running.
This all makes sense. What does not make sense
is the tailoring of total loop resistance
by selection of wire and tailoring of a specific
circuit breaker to achieve a "safe" reaction
to an overload.
Of course, none of this speaks to mechanical
issues in this product's design. It does give one
pause to consider the effectiveness of product
support when difficulties are identified in
the field. It's also alarming that the designer
finds it necessary to become secluded from the
customers that need a better understanding of
product characteristics than can be offered by
the present spokesperson.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 4
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| Subject: | Re: Relay vs Continuous Duty Contactor |
At 10:04 AM 4/10/2009, you wrote:
>
>It is for various reasons...possibly an essential bus alternate feed
>(14 amp continuous, 23 max intermittent) or for a separate dedicated
>avionics bus that powers redundant avionics equipment with similar
>bus loads (no worries..."essential" avionics are not switched). I
>know my essential load and architecture may differ from other
>people's objective, but I'm good with it.
The S704-1 would work fine
>Question is this...for that type of rating (14 amp continuous, 24
>max intermittent) for something that is going to be switched on and
>left on the the flight, what is the preferred contactor/relay?
>1) S701 (don't like the hefty current draw).
>2) S704
>3) A similar automotive relay. Any reason why something like the
>below wouldn't work just fine?
>
>http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=171460&
The S701-1 contactor is not suite to the tasks
you've cited. Relays of the class that includes
the S704-1 are sold by a host of sources including
those you've noted. Given the once-per-flight-cycle
operating duty, you're not going to loose one of
these relays to contact damage induced by 'overload'.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 5
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Bob
I have used all three models of IVO Props over the years, and I like
the design because of the simplicity and cost.
The attached PDF shows the construction of the prop hub and the wiring
that controls it.
I have found that if the toggle switch is held after the prop hits the
mechanical stops the circuit breaker will pop regardless of the
length of wire.
The best method of setting prop pitch in the air or on the ground is
to use an ammeter in series rather than just watching RPM's. This
also can prevent breaker tripping. The problem here is finding a
suitably scaled ammeter, in a compact size. Anyone?
I have trimmed the wire length to what is required in two out of three
installations without any apparent adverse effect.
Jim
On 10-Apr-09, at 9:06 AM, Robert L. Nuckolls, III wrote:
> >
>
> Ron: When the system is not being used it is 3 amp.
>
> BN: What is drawing current when the prop pitch motor
> is not running?
>
> Ron: This is a good questions but I do not have an answer for it.
> 3 x 8 = 24 amp when the circuit breaks. Reaches the stop at 15
> amp.
>
> BN: I'm still trying to understand the amount of
> energy required to satisfy in-flight operating
> requirements. It would stand to reason that
> normal running currents (motor in motion and
> free of the mechanical stops) are a small
> fraction of stall current (motor energized
> but prevented of motion because it is
> jammed).
>
> Hmmmm . . . I take it you are not the designer
> for this product's electrics. Can I have some
> conversation with the designer or at least someone
> who has understanding of the physics of this
> system?
>
> I'm thinking there are easy things you can do
> electronically to improve on the system's
> integrity and eliminate installation variability/
> error to achieve advertised performance.
>
> Ron: I found the system is using 3 amps when there is no load on the
> spool.
> This is when it goes through neutral transition between positive pitch
> and negative pitch from neutral. When the switch is not used there
> is no
> current.
>
> The designer has moved to a remote secluded location where he can
> work on other inventions without any distractions. That is why I
> am doing my best to answer your questions without bothering him.
> There are no plans to change or modify our propeller design at this
> time.
>
> -----------------------------------
>
> Okay, based on this limited exchange I have to deduce
> that the gentleman has but a rudimentary knowledge
> of how the product works. He is unable to discuss
> the physics of the motor's performance at or near
> stall with any notions of improving on user-
> friendliness. One noteworthy design goal would be
> to eliminate the requirement for fine tuning the
> resistance in hookup wire and/or sizing a specific
> style of breaker. This feature alone would get
> him tossed out of a design review meeting at
> any of the places I've worked.
>
> My best guess is that the motor draws 3A at
> the "no-load" point roughly centered on min-
> max prop pitch. Departures either direction
> from neutral winds up the springs causing motor
> current to rise. Peak current happens at
> some point just before the system hits the
> mechanical stops. There is no current draw
> when the motor is not running.
>
> This all makes sense. What does not make sense
> is the tailoring of total loop resistance
> by selection of wire and tailoring of a specific
> circuit breaker to achieve a "safe" reaction
> to an overload.
>
> Of course, none of this speaks to mechanical
> issues in this product's design. It does give one
> pause to consider the effectiveness of product
> support when difficulties are identified in
> the field. It's also alarming that the designer
> finds it necessary to become secluded from the
> customers that need a better understanding of
> product characteristics than can be offered by
> the present spokesperson.
>
>
> Bob . . .
>
> ----------------------------------------)
> ( . . . a long habit of not thinking )
> ( a thing wrong, gives it a superficial )
> ( appearance of being right . . . )
> ( )
> ( -Thomas Paine 1776- )
> ----------------------------------------
>
>
Message 6
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At 11:40 AM 4/10/2009, you wrote:
>Bob
>
>I have used all three models of IVO Props over the years, and I like
>the design because of the simplicity and cost.
>
>The attached PDF shows the construction of the prop hub and the wiring
>that controls it.
>I have found that if the toggle switch is held after the prop hits the
>mechanical stops the circuit breaker will pop regardless of the
>length of wire.
>
>The best method of setting prop pitch in the air or on the ground is
>to use an ammeter in series rather than just watching RPM's. This
>also can prevent breaker tripping. The problem here is finding a
>suitably scaled ammeter, in a compact size. Anyone?
Perhaps one of these paired with the appropriate shunt
sized for max load?
https://matronics.com/aeroelectric/Catalog/AEC/9007/9007.html
>I have trimmed the wire length to what is required in two out of three
>installations without any apparent adverse effect.
I would have guessed that . . .
I've designed actuator control systems designed to
limit travel with hard stops as opposed to limit
switches. One technique involves a small constant
current limit module that allows one a few percent
more than max operating current to flow. This value
is generally well under the value of the protective
circuit breaker. Further, performance in both normal
and fault modes is independent of breaker or wire
selection.
If you'd like to experiment with such a system, I'd
be pleased to support the effort with a proof
of concept limiter.
Another option would be to evaluate the polyswitch.
It's successful incorporation would emulate the
electric window risers on most cars. Those systems
don't have limit switches either. They depend on
operator response to release the switch in some
reasonable time after window limits are reached.
But if the operator is slow, the mechanism jams
or the switch sticks, the polyswitch keeps all
the smoke inside the wires.
This product's relative success in the field shows
a lot of promise. It's too bad that the business
model for its production is not more conducive
to the fine tuning of a recipe for success.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
Message 7
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| Subject: | E-Bus Alt Feed wire size |
RV8 with aft mounted battery and Z11 design. How much larger should the wire be
from battery to "Always on Buss" and from "Always on Buss" to "E Bus Alternate
Feed"? I estimate 20amp draw max from the E Bus.
I've read about the Z32 Heavy Duty E bus Feed and would prefer to not have to do
this. Even considering placing the battery on the firewall if I have to.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=238646#238646
Message 8
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Does a Ford-type alternator self excite? If not, how much battery
voltage is needed to excite it?
-----
Roger Cole
rcole927@earthlink.net
N76426
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