Thomas Compressor

[yara92]

If we use Thomas Compressor using the PCM it is stop and wirking many time befor the Tanks is full.
I am trying to wire Thomas Compressor with SPIKE. with Power Distribution Panel 20 A .
is it O.K.

[Mike Marandola]

It's ok. Check R37 and R42

[Al Skierkiewicz]

Mohamed,
You can replace the 20 amp fuse in the Spike with a 20 amp circuit breaker for the compressor only. I highly recommend you make the change.

[Richard Wallace]

I support Al's recommendation to replace 20A fuses with 20A snap action breakers in Spike relays that feed compressors, especially the Thomas 405ADC38/12.

Look here (http://www.chiefdelphi.com/forums/showthread.php?p=1438207#post1438207) for some test data that may help understanding why this recommendation is important.

[rich2202]

Which Thomas Compressor?

R68 Compressed air on the ROBOT must be provided by one and only one compressor. Compressor specifications may not exceed nominal
12VDC, 1.05 cfm flow rate.

[yara92]

Wiring the Compressor/ to
The Power Distribution Panel
What about Pressure Switch can we use Pneumatics Control Module.

[tStano]

If you wire the compressor to the PDP, you want to wire your switch to the DIO on the robo-rio so you can control it in your code. If you were to wire it to the PCM, it would be difficult to access the pressure switch value.

If you wire the compressor to the PCM, then you should wire the pressure switch there as well.

[GeeTwo]

We aren't using any pneumatics this year, but I have been in on several support threads. While using the spike to control the compressor is legal, it is really not the best solution. The PCB has circuitry to dampen the transient as the motor starts up, reducing the likelihood of tripping the fuse/breaker in the first place. I'm a "late adopter" who only uses something new when it is either mandatory or a clear improvement over the old-and-trusted. From what I've read, I'd rather use the PCB to control the compressor this year. If you decide to go the Spike route, a breaker rather than a fuse is a must!

[yara92]

I understand what you say, I have problem that we use the Thomas Compressor, 1/10 HP Model: 405ADC38/12 it is not working until it up 120 PSI about 70 psi stooping then after a while continue working.
So I don’t know where is the problem . I use the wiring PCM

[rich2202]

Thomas Compressor, 1/10 HP Model: 405ADC38/12

That compressor is rated for 100 psi. It will likely not stop running until the thermal switch on the compressor stops it. And then, it will not restart until the thermal switch resets.

The Nason pressure switch trips around 115 psi, well above the rated pressure of the compressor. It should not pressurize the system to the "fully charged" 115 psi level.

I don't know whether it is allowed to adjust the Nason switch to trip at a lower psi.

[FrankJ]

That compressor is rated for 100 psi. It will likely not stop running until the thermal switch on the compressor stops it. And then, it will not restart until the thermal switch resets.

The Nason pressure switch trips around 115 psi, well above the rated pressure of the compressor. It should not pressurize the system to the "fully charged" 115 psi level.

I don't know whether it is allowed to adjust the Nason switch to trip at a lower psi.

If this is the old FRC compressor, it will run to 120 PSI, no problem. The pressure switch is sealed. It is somewhat adjustable, but it would no longer be First legal. Since the rules require a specific part number, you cannot order it with a lower set pressure. Lot of discussion about this last year.

[yara92]

It It doesn't work by
Compressor Recharge Current Test Bench Set Up
test set up 48.pdf

[Al Skierkiewicz]

Mohamed,
There could be one or two things that are having an issue here. There is a thermal breaker inside the compressor that takes several minutes to reset once it trips. If you block the air slots on the side and end of the compressor, it will over heat. We are also unsure if the PCM can handle high current for this compressor. I would suggest you connect the compressor directly to the PDP through a 20 amp breaker please. See if it runs for a longer period than when controlled. It should reach well above 120 psi. That compressor is rated for 100psi but can easily pump up to 150 psi if it runs continuous.
The Nason pressure switch is not adjustable. The adjustment that people talk about simply sets the trigger for the internal microswitch. If mis-adjusted it will either not start or not shutoff. The factory makes the correct adjustment during production and then seals the adjustment screw.
It is also possible that you have an electrical issue between the PDP, the PCM (if you are using one) and the compressor. If one of the connections is loose, it will eventually heat up and fail intermittently.

[ozrien]

Mohamed,
There could be one or two things that are having an issue here. There is a thermal breaker inside the compressor that takes several minutes to reset once it trips. If you block the air slots on the side and end of the compressor, it will over heat. We are also unsure if the PCM can handle high current for this compressor. I would suggest you connect the compressor directly to the PDP through a 20 amp breaker please. See if it runs for a longer period than when controlled. It should reach well above 120 psi. That compressor is rated for 100psi but can easily pump up to 150 psi if it runs continuous.
The Nason pressure switch is not adjustable. The adjustment that people talk about simply sets the trigger for the internal microswitch. If mis-adjusted it will either not start or not shutoff. The factory makes the correct adjustment during production and then seals the adjustment screw.
It is also possible that you have an electrical issue between the PDP, the PCM (if you are using one) and the compressor. If one of the connections is loose, it will eventually heat up and fail intermittently.

I've tripped the internal compressor breaker by blocking the compressor's output air port, with a PCM. This is part of testing.

Do not connect the compressor directly to the PDP. Please read the PDP's User's Guide, which states not to do this.

[Al Skierkiewicz]

Oz,
I made the suggestion to try and diagnose the issue. If the PDP cannot handle the current then it cannot handle a CIM either. Connecting to the PDP through a 20 amp breaker for testing at least gives some electrical protection. We need to know where to look to suggest a fix.
Blocking the output port cannot not provide the necessary testing as it simply forces the piston to bypass compressed air. I would suspect that run current would only rise slightly in this condition. I am guessing that what is at issue here is a low voltage condition that is overheating the compressor armature.

[ozrien]

Oz,
I made the suggestion to try and diagnose the issue. If the PDP cannot handle the current then it cannot handle a CIM either. Connecting to the PDP through a 20 amp breaker for testing at least gives some electrical protection. We need to know where to look to suggest a fix.
Current is not the problem. That's not what the User's Guide suggests, and not what I posted.

My recommendation is find another way to direct-power the suspect compressor for the purpose of testing.

[Al Skierkiewicz]

Oz,
Can you describe how connecting the compressor through a Spike is any different than connecting the compressor directly to the PDP? The Spike is a relay with no other electronics in series with the load other than the breaker installed in the Spike.

[ozrien]

Oz,
Can you describe how connecting the compressor through a Spike is any different than connecting the compressor directly to the PDP? The Spike is a relay with no other electronics in series with the load other than the breaker installed in the Spike.
Just because a component is not in series doesn't mean it's not relevent. The Spike's catch diode is one example of this.

[Al Skierkiewicz]

The Spike's catch diode is one example of this.
???

[Mike Copioli]

???

Al,

The Spike has a suppression diode at the motor terminals. This diode clamps the inductive flyback that happens during both the freewheeling period and direction changes.

When a motor is connected directly to the PDP, the flyback that may occur during a breaker trip or simply from hot connecting the load may cause damage to the current sense IC's inside the PDP.

This is why we document this on more than one page in the user manual. CSA's and inspectors should be made aware of this. I would recommend that every inspector and CSA reads the documentation thoroughly.

[Al Skierkiewicz]

Mike,
As there is no rule that covers this, there is nothing on the inspection checklist for this item. I m not aware of any diodes on the motor output of the Spike, I believe there is an MOV, the same as the Victor. Is this what Oz is referring to?

[Mike Copioli]

Mike,
As there is no rule that covers this, there is nothing on the inspection checklist for this item. I m not aware of any diodes on the motor output of the Spike, I believe there is an MOV, the same as the Victor. Is this what Oz is referring to?

Al,

The Spike has a suppression diode at the motor terminals. This diode clamps the inductive flyback that happens during both the freewheeling period and direction changes.

When a motor is connected directly to the PDP, the flyback that may occur during a breaker trip or simply from hot connecting the load may cause damage to the current sense IC's inside the PDP.

This is why we document this on more than one page in the user manual. CSA's and inspectors should be made aware of this. I would recommend that every inspector and CSA reads the documentation thoroughly.

I have no better way to explain this.

[Richard Wallace]

The Spike has a suppression diode at the motor terminals. This diode clamps the inductive flyback that happens during both the freewheeling period and direction changes.
Mike, thanks for the reference to PDP documentation -- it is well presented and definitely worth reading through by all interested FRC participants who work with the control system. Students, mentors, robot inspectors, CSAs, FTAs, etc. The new control system is a wonderful advance over what we've used before.

Since you have some detailed knowledge of the Spike relay that is not mentioned in its doc (http://content.vexrobotics.com/docs/spike-blue-guide-sep05.pdf), can you tell us a little more about the suppression diode at its M+, M- terminals? I'd be interested in several of the specs for that diode, including leakage current, reverse voltage (clamping, avalanche, standoff, etc.), parasitic capacitance and inductance, energy ratings (single and repetitive), and anything else you know of that is pertinent to the protection it can offer against recovery voltage spikes produced when the Spike interrupts current to an inductive load. If those specs are not easily available to you, but you do have an example part to look at (outside of its case), can you tell us the manufacturer's part number of that suppression diode?

Thanks again for sharing detailed knowledge of FRC control system components.