Motor Reversing Intermittent Duty DPDT Solenoid Relay

[MikeMl]

Mike,
I'll try what you told me in the next 2-3hrs and will let you know. I was going through the link that you gave, what do I do in place of the push button?
Thanks.

Let me draw something up...

 

[armenon]

Thank you Mike for the help & effort. I have been trying my best but it is still falling short.

 

[armenon]

Let me draw something up...

Mike,

Are the two attached pics any different?

 

[alec_t]

Here's an alternative solution:

 

[MikeMl]

I have it drawn, simulated, and working but I need to know:

What are the coil voltages of the Cole-Hersee 24450 double contactor (12V)?
What is the main supply voltage (12V?)


Going out to dinner so it maybe tomorrow before I get back to this.

 

[armenon]

I have it drawn, simulated, and working but I need to know:

What are the coil voltages of the Cole-Hersee 24450 double contactor (12V)?
What is the main supply voltage (12V?)


Going out to dinner so it maybe tomorrow before I get back to this.

Yes, 12V. I'll think over it too and we can discuss it tomorrow.

Thanks.

 

[armenon]

Here's an alternative solution:
View attachment 75381

Alec,
Thanks for the diagram. But I have to stick to the relays. Transistors & diodes would not be an option for me on this.

 

[kinarfi]

As I see it, you need a second timer, maybe a third, 1.5 sec, so as timer 1 switches from forward to reverse, your second timer delays the application of power to the contactor for 1.5 sec.
Question for you about the contactor, how much power (amps) does it pull and how hot is it getting? Your contactor has a 5 min on, 5 min off duty cycle, and probably gets real hot. Another question is how many amps does you fan pull, My guess is around 15 to 20 if it's on a ATV. I realize you don't care for electronics, but I would recommend replacing your contactor which will probably fail in short order due to burning up and change over to FET H Bridge. If you're interested, I'd be glad to help you, I have replaced all the relays on my Joyner Trooper with FETs.
Kinarfi
http://www.pexsupply.com/ICM-Contro...stable-Delay?gclid=CMjPjZ_Wg7kCFck7MgodAFwAww

 

[MikeMl]

Yes, 12V. I'll think over it too and we can discuss it tomorrow.

Ok, attached is a relay-only based design and simulation.

1. The timer is set up to free run with 1.5s On and 90s Off (backwards from what you were thinking). The timer function is simulated in the dashed box on the left.

2. It takes a total of three relays between the timer and the Cole-Hersee contactor. Relay U3 is a DPDT 12Vdc relay. It is used to invert the signal from the timer, gate the power to the motor, and serves as the "push-button" contact to trigger the relay toggle (per the linked web page). Note the green trace V(B+). That shows when the motor will receive power (timer output inverted). Note that the current rating of U3 must be sufficient to switch the motor.

3. Relays U1 and U2 are 6Vdc DPDT relays that are effectively wired in series (per the linked web page). They form the toggle (flip flop).

4. I didn't show all of the details inside the motor contactor in the dashed box on the right, but I did show the current to the two coils I(L1) and I(L2). Note that the two coils are alternately pulsed (during the 1.5s part of the timer cycle). Don't worry about the sliver; it is too narrow to effect the coils. The alternating nature of these pulses is what reverses the motor. Per the earlier suggestion, you will have to lengthen the 1.5s period to allow the motor to coast down before reversing it...

 

[kinarfi]

Mike, your attached thumb nails are always interesting, would it be possible for you to always attach the .asc file also, I would sure appreciated it as many of your sims have been very educational.
Kinarfi

 

[MikeMl]

Mike, your attached thumb nails are always interesting, would it be possible for you to always attach the .asc file also, I would sure appreciated it as many of your sims have been very educational.
Kinarfi

Here t'is: The .asc file, the relay.asy, and the relay sim model. If you unzip into a new folder, it should run.

 

[kinarfi]

Thanks Mike

 

[armenon]

As I see it, you need a second timer, maybe a third, 1.5 sec, so as timer 1 switches from forward to reverse, your second timer delays the application of power to the contactor for 1.5 sec.
Question for you about the contactor, how much power (amps) does it pull and how hot is it getting? Your contactor has a 5 min on, 5 min off duty cycle, and probably gets real hot. Another question is how many amps does you fan pull, My guess is around 15 to 20 if it's on a ATV. I realize you don't care for electronics, but I would recommend replacing your contactor which will probably fail in short order due to burning up and change over to FET H Bridge. If you're interested, I'd be glad to help you, I have replaced all the relays on my Joyner Trooper with FETs.
Kinarfi
http://www.pexsupply.com/ICM-Contro...stable-Delay?gclid=CMjPjZ_Wg7kCFck7MgodAFwAww

Kinarfi,
Thank you for the information. The fan draws about 6-7amps in both the forward & reverse direction.
I had initially tried 2 timers and had adjusted the time. It worked on 1 cycle but thereafter there is a time gap because of the overlap of the timing on the timers.
Regarding the contactor, I don't know how hot it gets.
For me the duty cycle is 90sec ON, 1.5sec OFF (forward direction of blade), then next cycle again 90sec ON, 1.5sec OFF (reverse direction) & it continues till there is a failure or deterioration in the fan performance.
I would prefer not using any diodes, FETs. I am not sure either if that is possible. I will look for your further guidance.
Thanks.

 

[armenon]

Ok, attached is a relay-only based design and simulation.

1. The timer is set up to free run with 1.5s On and 90s Off (backwards from what you were thinking). The timer function is simulated in the dashed box on the left.

2. It takes a total of three relays between the timer and the Cole-Hersee contactor. Relay U3 is a DPDT 12Vdc relay. It is used to invert the signal from the timer, gate the power to the motor, and serves as the "push-button" contact to trigger the relay toggle (per the linked web page). Note the green trace V(B+). That shows when the motor will receive power (timer output inverted). Note that the current rating of U3 must be sufficient to switch the motor.

3. Relays U1 and U2 are 6Vdc DPDT relays that are effectively wired in series (per the linked web page). They form the toggle (flip flop).

4. I didn't show all of the details inside the motor contactor in the dashed box on the right, but I did show the current to the two coils I(L1) and I(L2). Note that the two coils are alternately pulsed (during the 1.5s part of the timer cycle). Don't worry about the sliver; it is too narrow to effect the coils. The alternating nature of these pulses is what reverses the motor. Per the earlier suggestion, you will have to lengthen the 1.5s period to allow the motor to coast down before reversing it...

Mike,
Thanks a lot. I went through the attached diagram.
Is there any way we can avoid diodes & resistors in this set up? Can we just do it with relays?
In the diagram what does "100" mean in the Cole Hersee DPDT relay?
Also you have stated the inverse of the duty cycle above. (1.5sec ON, 90sec OFF)

I tried simulating it in LTSpice, but is shows an error "Can't find definition of 1N4001".

 

[alec_t]

Just for the simulation you can use any other diode instead of the 1N4001.

 

[MikeMl]

...Is there any way we can avoid diodes & resistors in this set up? Can we just do it with relays?

The diodes are there to protect the relay contacts. Without the diodes, the contacts will arc because you are switching inductive relay coils and very inductive contactor coils every time a relay/timer contact opens. You want the relays to last longer longer than the motor you are testing, so use the diodes as shown.

In the diagram what does "100" mean in the Cole Hersee DPDT relay?

That is the inductance value (100mH) I used for the two coils in the Cole-Hersee Contactor for simulation. You are not building the Contactor, so ignore everything inside the dashed box, including the resistor. The resistor is there to act as a pull-down resistor (in-place of the motor) just so the simulation shows the correct voltage.

Also you have stated the inverse of the duty cycle above. (1.5sec ON, 90sec OFF)

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,..

Don't forget my caution that Relay U3's contact is switching the motor on/off (not the contactor, it is just reversing the connections to it during the time the motor is coasting), so the U3 contacts must be rated to handle the motor...

I tried simulating it in LTSpice, but is shows an error "Can't find definition of 1N4001".

Use the MURS120 that is part of the normal LTSpice library. I forgot that I had augmented my version of the library with thousands of extra diodes when I made the .zip file.

 

[armenon]

The diodes are there to protect the relay contacts. Without the diodes, the contacts will arc because you are switching inductive relay coils and very inductive contactor coils every time a relay/timer contact opens. You want the relays to last longer longer than the motor you are testing, so use the diodes as shown.


That is the inductance value (100mH) I used for the two coils in the Cole-Hersee Contactor for simulation. You are not building the Contactor, so ignore everything inside the dashed box, including the resistor. The resistor is there to act as a pull-down resistor (in-place of the motor) just so the simulation shows the correct voltage.




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 100%. 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,..



Use the MURS120 that is part of the normal LTSpice library. I forgot that I had augmented my version of the library with thousands of extra diodes when I made the .zip file.

Mike,
Can I use two 12V DPDT relays instead of 6V DPDT relays that you have mentioned. (All 3 DPDT 12V relays - same?)
Thanks.

 

[MikeMl]

Mike,
Can I use two 12V DPDT relays instead of 6V DPDT relays that you have mentioned. (All 3 DPDT 12V relays - same?)
Thanks.

You can try it, but I predict it will not work. (Confirmed by simulation) If you read the linked web page, the two relays are effectively in-series, which means they get half the 12V each. It is unlikely that a 12V relay will pull-in with only 6V applied to the coil.

You could buy three 6V relays, and put a resistor in-series with the coil of U3 to drop its coil voltage to 6V.

 

[armenon]

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.

 

[ericgibbs]

Mike,

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

Eric