Re: Can someone help me put this together?


"Fred Bloggs" <nospam@xxxxxxxxxx> schreef in bericht
news:4360D15F.3040609@xxxxxxxxxxxxx
>
>
> John Fields wrote:
>> On Wed, 26 Oct 2005 12:04:41 -0500, John Fields
>> <jfields@xxxxxxxxxxxxxxxxxxxxx> wrote:
>>
>>
>>>On Wed, 26 Oct 2005 14:40:47 GMT, Fred Bloggs <nospam@xxxxxxxxxx>
>>>wrote:
>>>
>>>>That works- but is there an AC solution? Motor is heavily geared and
>>>>turns slowly- stops on a dime.
>>>
>>>---
>>>Yes.
>>>
>>>Use an adjustable delay-on-make timer like an ICM Controls ICM102 or
>>>a WW Grainger 4E233,(they're the same part) like this:
>>>
>>>
>>>SWITCHED MAINS IN>---+------+
>>> | | +-----+ |
>>> |TIMER| | +-----+ | | O
>>> | |K1
>>> [COIL]- -|<---O
>>> | |
>>> O | |
>>> S1 |<- - -[MOTOR]
>>> O | |
>>> | |
>>>RETURN>--------------+-----------+
>>>
>>>That way, If S1 is closed because the motor stopped when it (S1)
>>>closed, the timer will block the flow of current into the coil of
>>>K1, keeping K1 de-energized until the motor turns enough to release
>>>S1.
>>
>>
>> ---
>> Aarrghhh...
>>
>> There's still a problem in that if the timer keeps the coil from
>> being energized for a while when the switched mains in goes hot
>> _and_ S1 is made, the same thing'll happen when S1 is made by the
>> motor riding over it, since it was open before that and the timer
>> was waiting for a current path to start its timeout. That is, when
>> the timer sees mains voltage across itself (and passes just enough
>> current to make its timer work without pulling in K1) K1 won't be
>> able to pull in until S1 is released, but by then it'll be too late,
>> and the motor will never stop.
>>
>> Intrigueing problem to try to solve from just the AC side...
>>
>> More tomorrow...
>>
>> Si Dios quiere.
>>
>
> Right- I was wondering about that. The only way this can work is to detect
> a transition from open to close and and vice versa in S1, any control
> relying on S1 static position or polarity of transition will fail.
> Forgetting about any particular hardware for the moment, if you can
> configure a detection circuit that is somehow "armed" by the sequence of
> S1 moving from initial to opposite state and then triggers the
> self-latching NC power relay when S1 returns to the initial state, this
> should do it. If power first comes up with S1 open, then the trigger arms
> when S1 closes and triggers motor off when S1 re-opens. If power comes up
> with S1 closed, the trigger arms when S1 opens, and triggers when S1
> re-closes. The end result is that the motor always stops at the SW
> position after making at most one revolution. If you want the motor to
> fall into always stopping when S1 closes, then you could a timer that
> applies to the arming logic so that if S1 was open initially, but the
> motor has run a minimum predetermined time, the trigger logic will fire on
> first closure.
>


Can't help but giving it a second look. I'm sure all simple solutions may
run into timing or exception problems like I said before. The solution below
is not very simple but should work always.


+--------+---------+---------+
| | | |
| | | |
.-. _|_ _|_ _|_
( M ) |_/_|- |_/_|- |_/_|-
'-' |A |B |S
| | | |
| | | |
+----------------------+ |
| | | | |
| | | | |
| | | | |
| +--------o / o / o /
| | / / /
| | /a1 /a2 / SW1
| | o o o
| | | | |
| | +----+----+ |
| | | |
| | | |
o /o /o |
/ / |
/ b / s |
o o |
| | |
+-------------+------------------+--
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

S can be omitted when SW1 has a normally closed contact that can stand the
motor current, so SW1 can replace the s-contact. If you have to use the
S-relay, it should be fast with respect to the A- and B-relays.

petrus bitbyter






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