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Old 09-20-2011, 01:12 AM   #11
skinny
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Jun 2009
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Quote:
Originally Posted by cruelkix View Post
A march pump should not be drawing 3.8 amps.

It sounds like your wiring is messed up somehow. You best bet for getting a solution would be posting a wiring diagram and a picture of your control panel I would think.
I agree it should not be drawing that much current. Here is a quick and ugly wiring diagram of this section of my rig. The ground is connected just not shown.
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When the pump is plugged into the top plug which is always hot, it runs fine and draws the 1.45a. When I plug it into the bottom outlet with the ssr switching the hot leg, it draws the 3.8a and doesn't turn.



 
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Old 09-20-2011, 04:21 AM   #12
cruelkix
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May 2009
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Quote:
Originally Posted by skinny View Post
I agree it should not be drawing that much current. Here is a quick and ugly wiring diagram of this section of my rig. The ground is connected just not shown.
Attachment 33958
When the pump is plugged into the top plug which is always hot, it runs fine and draws the 1.45a. When I plug it into the bottom outlet with the ssr switching the hot leg, it draws the 3.8a and doesn't turn.
I don't trust the plug I guess. Try taking them out of parallel and putting the SSR inline with the top plug that has worked before, don't connect anything to the bottom plug.



 
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Old 09-20-2011, 11:24 PM   #13
skinny
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Jun 2009
Texas
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Quote:
Originally Posted by cruelkix

I don't trust the plug I guess. Try taking them out of parallel and putting the SSR inline with the top plug that has worked before, don't connect anything to the bottom plug.
Same result on top plug when controlled by ssr. I am thinking it is an issue with the lot of ssrs I have. I think I am going to order a relay board and try that. For 8 bucks, and I don't see what it would hurt.

 
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Old 09-21-2011, 05:58 PM   #14
audger
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., Connecticut
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a SSR will show 120v across the two control terminals even when its supposed to be off. this is normal. what is not normal is the voltage dropping to 75v when the SSR switches on. it sounds like your SSR is faulty and is partially blocking the voltage.

the high amperage reading you have is a combo of the low-voltage problem (when you halve the voltage, the amperage requirement doubles; P=IxR; so its trying to make up for the lack of voltage by essentially requesting more amperage) and the fact that the pump is not spinning.
during the space of time between when power is first supplied, and when the pump reaches operating speed, the pump (or any motor) will pull much more than its normal operating amperage. since its never getting up to operating speed, its stuck in this startup mode pulling extra amperage and burning up the brushes and contacts on the motor.

undervolting an a/c motor in this way is very bad for it, and you should stop using the pump on that relay immediately before you do any (more) damage to it, and untill you find and fix the problem.

are your SSRs rated for switching 120v AC? you sure they arent DC? the components that control the main voltage (mosfets) are arranged differently for AC than for DC; because A/C alternates, A/C SSRs use two mosfets tied to the same source with different drains (as opposed to DC SSRs which use only one mosfet, or a more parrallel configuration). so it would make sense trying to pass 120v AC thru a DC SSR that you would get around half the voltage, as it would be blocking most of the current in one direction but not the other, effectively converting it into DC.

 
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Old 09-21-2011, 06:29 PM   #15
P-J
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Quote:
Originally Posted by audger View Post
...
are your SSRs rated for switching 120v AC? you sure they arent DC? the components that control the main voltage (mosfets) are arranged differently for AC than for DC; because A/C alternates, A/C SSRs use two mosfets tied to the same source with different drains (as opposed to DC SSRs which use only one mosfet, or a more parrallel configuration). so it would make sense trying to pass 120v AC thru a DC SSR that you would get around half the voltage, as it would be blocking most of the current in one direction but not the other, effectively converting it into DC.
Good call on that one. That is a strong possibility.

To the OP... Do you have a link to your SSR source?

 
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Old 09-21-2011, 08:23 PM   #16
CidahMastah
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I accidentally bought output DC ssrs and they worked absolutely fine reading 238V as they should have on my system. Until one day the SSR toasted itself and Walker noticed I bought the wrong type. I put another DC output one in my control box and have been using it with no issues, but plan to replace it with the AC output one (bought 2 already), when the DC SSR in place frys.

I posted this mostly to illustrate that teh DC output SSR didn't half my 240 intended AC output. Also I would like to understand a bit more if there are any issues you see with my DC output that could cause issue with an autotune problem I am having (sorry to hijack a bit).

this was my SSR

I am not an electric guru, just learning.
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Old 09-21-2011, 08:44 PM   #17
skinny
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Jun 2009
Texas
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Quote:
Originally Posted by audger View Post
... it sounds like your SSR is faulty and is partially blocking the voltage.

the high amperage reading you have is a combo of the low-voltage problem (when you halve the voltage, the amperage requirement doubles; P=IxR; so its trying to make up for the lack of voltage by essentially requesting more amperage) and the fact that the pump is not spinning.
during the space of time between when power is first supplied, and when the pump reaches operating speed, the pump (or any motor) will pull much more than its normal operating amperage. since its never getting up to operating speed, its stuck in this startup mode pulling extra amperage and burning up the brushes and contacts on the motor....
That is pretty much what I was starting to think, a combination of low voltge and the normal starting current of a motor, causing the high amp readings.


Quote:
Originally Posted by audger View Post
...are your SSRs rated for switching 120v AC? you sure they arent DC? the components that control the main voltage (mosfets) are arranged differently for AC than for DC; because A/C alternates, A/C SSRs use two mosfets tied to the same source with different drains (as opposed to DC SSRs which use only one mosfet, or a more parrallel configuration). so it would make sense trying to pass 120v AC thru a DC SSR that you would get around half the voltage, as it would be blocking most of the current in one direction but not the other, effectively converting it into DC.
Quote:
Originally Posted by P-J View Post
Good call on that one. That is a strong possibility.

To the OP... Do you have a link to your SSR source?
These are the ones I have tried so far. I also have a couple i got from auber ins somewhere I plan on trying.
http://www.amazon.com/gp/product/B00...%20Depot%20Inc

 
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Old 09-21-2011, 10:33 PM   #18
mattd2
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Sep 2009
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Quote:
Originally Posted by CidahMastah View Post
I posted this mostly to illustrate that teh DC output SSR didn't half my 240 intended AC output. Also I would like to understand a bit more if there are any issues you see with my DC output that could cause issue with an autotune problem I am having (sorry to hijack a bit).

this was my SSR

I am not an electric guru, just learning.
What you say about not halfing your 240v is not exactly true. The DC SSR will only allow 1/2 of the phase cycle to pass so you will still get a peak voltage of 240V but only for 1/2 the cycle. This will effectly 1/2 the power as power is only flowing for 1/2 the cycle.
What is the autotune problem you have?

My guess on why the DC SSR fried is because for 1/2 the time you were trying to shove 240V the wrong way through it.

 
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Old 09-22-2011, 12:56 AM   #19
CidahMastah
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Quote:
Originally Posted by mattd2 View Post
What you say about not halfing your 240v is not exactly true. The DC SSR will only allow 1/2 of the phase cycle to pass so you will still get a peak voltage of 240V but only for 1/2 the cycle. This will effectly 1/2 the power as power is only flowing for 1/2 the cycle.
What is the autotune problem you have?

My guess on why the DC SSR fried is because for 1/2 the time you were trying to shove 240V the wrong way through it.
Quite possible.

The autotune issue I have is that when I went to autotune it, it passed the set point on the pid and went to a rolling boil and held it. On the PID, the auto read "0" for power on the automatic mode. However, it was a 100% boil. I cut the autotune out after waiting about 10-15 minutes and seeing no change in the boil strength. It never finished auto tune. I turne dautotune on at about 8degrees F below the set point. PJ was telling me I should have turned autotune on no with no more than 10F.

What bothered me was the reading of "0" for power on auto, yet full strength boil. I didn't take a reading with a multimeter, but it was evident the juice was flowing when it should have been off.

Currently I have a DC output ssr in the control panel. But plan to replace it soon, as I bought two replacement ac output SSRs. I left it in because I was brewing alot and had to wait for the replacement to arrive.
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Old 09-22-2011, 10:23 AM   #20
flananuts
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I had a similar issue when wiring a simple auber temp controller with a 120/240 v sir to control my freezer/lager chamber. I had the exact issues described. I ended up just using the internal auber relay because I could not get it to work properly. On your march pump in your setup, are they process controlled vs manual switching, hence the need for an ssr/relay?



 
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