Motor Reversing Intermittent Duty DPDT Solenoid Relay

[MikeMl]

Mike,
I changed the diode to MURS120 but when I try to simulate it, it won't do anything. I am not getting any error either.

The sim is likely running to completion. Are you then clicking on a circuit node to display the voltage in the plot pane?

 

[armenon]

Mike,

Changed to MURS120 , all works ok for me, just for confirmation.

Eric

Eric,
It is the first time I am using LTSpice. I right-clicked on the diode & selected MURS120 from the list of diodes. Is that the correct way of doing it? If yes, is there anything else that I need to pay attention to?
Thanks/

 

[armenon]

The sim is likely running to completion. Are you then clicking on a circuit node to display the voltage in the plot pane?

Mike,
I just selected the diode from the list of diodes. Then I clicked on the simulation icon. Is there anything else that I need to do to make it simulate properly. It's my first time using this tool. I am trying to figure it out.
Thanks.

 

[armenon]

The sim is likely running to completion. Are you then clicking on a circuit node to display the voltage in the plot pane?

Mike,
I wasn't clicking on the circuit node like you mentioned. Wasn't aware of that. I can see the plot now. I'll try this circuit diagram.
Thanks.

 

[armenon]

Mike,
I am in the process of ordering the 1N4001 diodes. Would that be a right choice for the set up. The fan draws about 8amps.
Thanks.

 

[MikeMl]

Mike,
I wasn't clicking on the circuit node like you mentioned. Wasn't aware of that. I can see the plot now. I'll try this circuit diagram.
Thanks.

After a sim is run, if you move the cursor to a component pin (try one end of a relay coil, for example), you should see the icon change to a "clamp-on-ammeter", and then if you click, the pin current will be added to the plot.

 

[MikeMl]

Mike,
I am in the process of ordering the 1N4001 diodes. Would that be a right choice for the set up. The fan draws about 8amps.
Thanks.

The motor current doesn't flow in any of the diodes; only the relay and solenoid coil currents, so a 1A diode will be fine. Since the diodes are reversed biased only to 12V (the supply voltage), then even the lowly 1N4001 will work fine. You can confirm this with the simulator...

 

[armenon]

The motor current doesn't flow in any of the diodes; only the relay and solenoid coil currents, so a 1A diode will be fine. Since the diodes are reversed biased only to 12V (the supply voltage), then even the lowly 1N4001 will work fine. You can confirm this with the simulator...

Thank you Mike.

 

[kinarfi]

This answers your question about the Cole-Hersee contactor getting hot. It says right on the data sheet that the duty-cycle to the coils must be less than 50%; you were driving it 90/91.5 = 98%. My version drives the coils for just 1.5s/91.5s ≈ 2%! I turned the timer period upside down to generate the short pulse required to flip the contactor during the time the motor is coasting,..

I had a contactor like this and with the way it is built, you can't change it's function, it has to have one or the other coil energized or nothing happens. At rest, both motor leads are at +12 volts and as you energize one of the coils, the lead on that side goes to ground. It's a very good relay for winches, but as it says, only for 5 minutes, on the one I had, the coil pulled 2 amps, 24 watts of heating, and there isn't enough surface area to dissipate the heat and mine did get so hot, I couldn't keep my finger on it!!
In your pictures on post #11, I see you have some definite purpose relays, and since the fan only draw ~7 amps, may I suggest you use 4 of them to power your fan, circuit drawing attached.

I showed the same two on delay timers as before, but there are other on delay timers out there, basically, the 91.5 timer you have will trigger the on delay timers which energize the 2 relays to send power to the fan, the diodes, as Mike stated are needed. Another timer is https://www.electro-tech-online.com/custompdfs/2013/08/70200052.pdf , it can be ordered for 12vdc and is load independent. There others also, depending on locale and budget.

 

[MikeMl]

I had a contactor like this and with the way it is built, you can't change it's function, it has to have one or the other coil energized or nothing happens. At rest, both motor leads are at +12 volts and as you energize one of the coils, the lead on that side goes to ground. It's a very good relay for winches, but as it says, only for 5 minutes, on the one I had, the coil pulled 2 amps, 24 watts of heating, and there isn't enough surface area to dissipate the heat and mine did get so hot, I couldn't keep my finger on it!!
...

Kinarfi is right about this contactor not working unless one coil is driven continuously. I got it mixed up with another similar one that has two coils where each coil is pulsed to change the state of the contactor. Bottom line is that the circuit I posted will not work with this contactor.

Even if I modified the circuit I posted such that the coils are powered alternatively, but for the entire 90s duration while the motor is running, the contactor would still overheat, because the total time the coils are powered is 98% of the time, not less than 50%.

One approach would be to not to use the Cole-Hersee contactor at all, and just use regular 12V relays.

Kinarfi makes a good point about the "braking" function of the Cole-Hersee contactor, where when neither coil is energized, the motor is shorted to stop it quickly. Kinarfi has one detail wrong, however. Both sides of the motor are connected to B- (gnd); not B+ (+12V). So the question for Armenon is "do you need dynamic braking"?

Here is a new version of my circuit. I have replaced the Cole-Hersee contactor with two new relays U4 and U5, both of which must have a contact rating of at least 10A. This circuit energizes one relay at a time, but only during the "run" time of the motor. See the plots of V(a) red trace and V(b) blue trace. Note the voltage across the motor V(M+,M-) green trace. There is no voltage applied (i.e. the motor is shorted) during dynamic braking.

To simulate this yourself, save the file Toggle1.asc in the same directory as you unzipped the earlier circuit into.

Some Caveats: What happens when your motor (fan) is running at speed, and then it is suddenly shorted? It should stop very quickly, but how large is the current through the shorting contacts? Does this mimic how the motor is actually used? If the current is big (too big for the relays), you might need to provide a "braking path" where a power resistor is switched in series with the motor during the off time, but where said resistor is shorted out during the run time...

 

[armenon]

I had a contactor like this and with the way it is built, you can't change it's function, it has to have one or the other coil energized or nothing happens. At rest, both motor leads are at +12 volts and as you energize one of the coils, the lead on that side goes to ground. It's a very good relay for winches, but as it says, only for 5 minutes, on the one I had, the coil pulled 2 amps, 24 watts of heating, and there isn't enough surface area to dissipate the heat and mine did get so hot, I couldn't keep my finger on it!!
In your pictures on post #11, I see you have some definite purpose relays, and since the fan only draw ~7 amps, may I suggest you use 4 of them to power your fan, circuit drawing attached.

I showed the same two on delay timers as before, but there are other on delay timers out there, basically, the 91.5 timer you have will trigger the on delay timers which energize the 2 relays to send power to the fan, the diodes, as Mike stated are needed. Another timer is https://www.electro-tech-online.com/custompdfs/2013/08/70200052.pdf , it can be ordered for 12vdc and is load independent. There others also, depending on locale and budget.

Kinarfi,
For my set up I need to run 8 fans at a time at 80C in an environmental chamber. I cannot use those 4 relays on 1 fan as in that case I would need 32 of them which is not possible.
So the DPDT solenoid relay (Cole Hersee) basically is not the right relay for my test?
Thanks by the way for the information.

 

[armenon]

Kinarfi is right about this contactor not working unless one coil is driven continuously. I got it mixed up with another similar one that has two coils where each coil is pulsed to change the state of the contactor. Bottom line is that the circuit I posted will not work with this contactor.

Even if I modified the circuit I posted such that the coils are powered alternatively, but for the entire 90s duration while the motor is running, the contactor would still overheat, because the total time the coils are powered is 98% of the time, not less than 50%.

One approach would be to not to use the Cole-Hersee contactor at all, and just use regular 12V relays.

Kinarfi makes a good point about the "braking" function of the Cole-Hersee contactor, where when neither coil is energized, the motor is shorted to stop it quickly. Kinarfi has one detail wrong, however. Both sides of the motor are connected to B- (gnd); not B+ (+12V). So the question for Armenon is "do you need dynamic braking"?

Here is a new version of my circuit. I have replaced the Cole-Hersee contactor with two new relays U4 and U5, both of which must have a contact rating of at least 10A. This circuit energizes one relay at a time, but only during the "run" time of the motor. See the plots of V(a) red trace and V(b) blue trace. Note the voltage across the motor V(M+,M-) green trace. There is no voltage applied (i.e. the motor is shorted) during dynamic braking.

To simulate this yourself, save the file Toggle1.asc in the same directory as you unzipped the earlier circuit into.

Some Caveats: What happens when your motor (fan) is running at speed, and then it is suddenly shorted? It should stop very quickly, but how large is the current through the shorting contacts? Does this mimic how the motor is actually used? If the current is big (too big for the relays), you might need to provide a "braking path" where a power resistor is switched in series with the motor during the off time, but where said resistor is shorted out during the run time...

Mike,
The duty cycle is 50% at 75amps/12V/25C. Then it states Max ON time - 30sec at 125A/12V & Max ON time - 0.5sec at 150A/12V. So I don't think 90sec/91.5sec should be a problem.
Both the motor terminals are not connected to ground, 1 is connected is connected to positive and the other to ground. That's how I am reading it.
Right now I am confused as to how I should now proceed.
I am not sure if the Cole Hersee is the right one as Kinarfi stated.

Also on the DPDT solenoid relay chart, it states that "Solenoid is designed to be activated only with a momentary switch". Would that be a problem?
Thanks.

 

[MikeMl]

Mike,
The duty cycle is 50% at 75amps/12V/25C. Then it states Max ON time - 30sec at 125A/12V & Max ON time - 0.5sec at 150A/12V. So I don't think 90sec/91.5sec should be a problem.

Look at the first attachment. I interpret note 4 to mean that if the load current is 75A or less, you cannot have the coils powered more than 50% of the time, and never more than 5min continuously without giving it a 5min rest. Since you want the motor(s) to turn CW for 90sec, off 2sec, turn CCW for 90sec, off 2sec, and repeat, you are violating the 50% spec. since the coils are powered 98% of the time... As Kinarfi pointed out, the heating of the contactor is due to the dissipation in the coils. It might be possible to reduce this.

Both the motor terminals are not connected to ground, 1 is connected is connected to positive and the other to ground. That's how I am reading it.

Look at attachment 2. Note where MTR FWD and MTR REV are connected. When neither coil is pulled-in (motor off, coasting, braking), the two normally closed contacts short the motor to terminal B- (Gnd).

Right now I am confused as to how I should now proceed.
I am not sure if the Cole Hersee is the right one as Kinarfi stated.

One other idea is to use this Contactor, but get around its power dissipation limit by initially driving the coil with 12V to slam it in, but then to reduce the coil voltage to a hold-in value which reduces the dissipation...

Also on the DPDT solenoid relay chart, it states that "Solenoid is designed to be activated only with a momentary switch". Would that be a problem?
Thanks.

Yes, your switch is almost continuous (98%)!

 

[MikeMl]

Armenon,

You haven't answered the most fundamental question: Does applying a Dead-Short to your motor(s) under test during the 1.5s you are reversing them mimic the way they are actually used?????

If you are trying to do a life test, you should be making the motors do what they do in the application; not what the Cole-Hersee contactor naturally does...

 

[kinarfi]

https://www.dropbox.com/s/1s3dw3ohfo0jt7n/20130709_122712.jpg
https://www.dropbox.com/s/eeplmx2313tzwfu/20130709_122740.jpg
These are the relays I replace my over heating contactor with. They are what controls the direction of my winch on my OHV.
I am not absolutely sure that these won't over heat also, but they will handle the current! I got them from eBay for around $6 each.
What is you budget. There are some contactor and definite purpose relays that are designed for your job.

 

[armenon]

Armenon,

You haven't answered the most fundamental question: Does applying a Dead-Short to your motor(s) under test during the 1.5s you are reversing them mimic the way they are actually used?????

If you are trying to do a life test, you should be making the motors do what they do in the application; not what the Cole-Hersee contactor naturally does...

Mike,
I am not very sure about that & I don't think so it happens in the application. I am not trying to do the test based on the Cole Hersee contactor. The test specification itself states that it should be 90sec ON,1.5sec OFF. I am looking for the failure mode & how long the motors would last before I see any failure. It's a validation test.
Thanks.

 

[armenon]

https://www.dropbox.com/s/1s3dw3ohfo0jt7n/20130709_122712.jpg
https://www.dropbox.com/s/eeplmx2313tzwfu/20130709_122740.jpg
These are the relays I replace my over heating contactor with. They are what controls the direction of my winch on my OHV.
I am not absolutely sure that these won't over heat also, but they will handle the current! I got them from eBay for around $6 each.
What is you budget. There are some contactor and definite purpose relays that are designed for your job.

Kinafi,
Well right now I am confused as to how to go about it. I am in FortWorth,TX. Can you tell me the contactors & the relays that you were talking about.
Thanks.

 

[kinarfi]

Motor Reversing Intermittent Duty DPDT Solenoid Relay-toggle1.jpg
Attached Files
File Type: asc Toggle1.asc (5.1 KB, 2 views)

Mike, as someone else said, my head is aching, I have been looking at your Toggle1.asc and trying to figure out you 2 6v relays in series used as a flip flop, Very interesting, but I sure would appreciate an explanation of how it works. I can see that it does, but I'm missing something and I believe an explanation would help turn on the light for me.
These done relay on a relay race at all do they?
Thanks,
Kinarfi

 

[armenon]

Kinarfi is right about this contactor not working unless one coil is driven continuously. I got it mixed up with another similar one that has two coils where each coil is pulsed to change the state of the contactor. Bottom line is that the circuit I posted will not work with this contactor.

Even if I modified the circuit I posted such that the coils are powered alternatively, but for the entire 90s duration while the motor is running, the contactor would still overheat, because the total time the coils are powered is 98% of the time, not less than 50%.

One approach would be to not to use the Cole-Hersee contactor at all, and just use regular 12V relays.

Kinarfi makes a good point about the "braking" function of the Cole-Hersee contactor, where when neither coil is energized, the motor is shorted to stop it quickly. Kinarfi has one detail wrong, however. Both sides of the motor are connected to B- (gnd); not B+ (+12V). So the question for Armenon is "do you need dynamic braking"?

Here is a new version of my circuit. I have replaced the Cole-Hersee contactor with two new relays U4 and U5, both of which must have a contact rating of at least 10A. This circuit energizes one relay at a time, but only during the "run" time of the motor. See the plots of V(a) red trace and V(b) blue trace. Note the voltage across the motor V(M+,M-) green trace. There is no voltage applied (i.e. the motor is shorted) during dynamic braking.

To simulate this yourself, save the file Toggle1.asc in the same directory as you unzipped the earlier circuit into.

Some Caveats: What happens when your motor (fan) is running at speed, and then it is suddenly shorted? It should stop very quickly, but how large is the current through the shorting contacts? Does this mimic how the motor is actually used? If the current is big (too big for the relays), you might need to provide a "braking path" where a power resistor is switched in series with the motor during the off time, but where said resistor is shorted out during the run time...

Mike,
Would the fan switch its polarity after each cycle if we use this circuit (5 relays circuit diagram)?

 

[MikeMl]

Mike,
Would the fan switch its polarity after each cycle if we use this circuit (5 relays circuit diagram)?

Yes. Look at the Green trace in this image:

That is the voltage applied to the motor terminals.