1336 Plus II VFD 2

[Krusher]

Has anyone had experience with this drive in cold weather. The A/B tech support says there is no low temp sensor, however on two occasions, at +5F the drive failed to start showing a high temp fault. After slightly warming the drive I was able to start. I'm thinking there might be a low temp sensor on the board. The tech guy thinks the high temp sensor is going bad. Basicly I would like a second opinion before replacing the sensor.

 

[jOmega]

Look at the drive specifications. In particular, look for the operating range (not storage) temperature.

If the minimum is 32°F (0°C) then there is very likely a logic inhibit for low temperature starting.

From the SPECIFICATION document for the Plus II,
the following ..

http://www.ab.com/manuals/dr/1336plus/1336f-sr001a-en-p.pdf

ENVIRONMENT:

Operating ambient temperature range:
0 C to 40 C (0 to 109 F) without derating.

you could also send an emial to: Steve Spaeth at Rockwell and ask about the ability to start the drive when the ambient temperature is below 32°F.

mailto: sspaeth@ra.rockwell.com

Hope this helps.

//

 

[dydt]

hi..
where is your drive mounted? if you find out that there is nothing wrong with the temp. sensors, is relocating the drive a possible solution? ...or installing a small heater inside the panel when temperature drops at a certain level..

dydt

 

[jraef]

Krusher
Although I know of no AFD that contains a low temp detector, it would be a good idea. In jOmega's post above he made a typo on the temperature conversion; 0C = 32F, not 0F. There is a reason why NO drive can be rated for OPERATION below freezing. Are you aware that by energizing that drive at 5F you are risking severe damage to the capacitors? If the electrolyte in the cap core freezes, it creates a dead short. The caps will explode, and I have witnessed it as a particularly violent event, sending the AFD cover sailing off about 100 feet! You don't even need to give the drive a run command, it happens when you just put power on the line terminals.

Come to think of it, one thing I know about AB 1336 AFDs is that on larger sizes they use an SCR front end rectifier. They use it to ramp initial applied voltage into the DC bus so as to not stress the caps (as opposed to a charging resistor as many others use). With this method, it is possible that some smart engineer at AB added a low temp cut off switch to the SCR firing board so that you cannot energize the DC bus below freezing. Great idea if they did. I have found that several AB service techs were not even aware that the 1336's had an SCR front end, they just assumed it was a diode bridge. I had to learn it from the factory people once when I had a failure in the field. That could explain why your tech was not aware of any low temp device (if any).

Generally, if you need to operate a drive at below freezing I recommend the following. Go to a refrigeration parts distributor at pick up a "freeze-stat". This is a thermostat which operates for freezers where the contact CLOSES on temperature rise. Find one with a range that works at around 40F, and place the sensor bulb near the top of the AFD heat sinks. Wire it into a contactor for line power and add a heater so that when power is applied, only the heater is energized until the freeze-stat bulb sees 40F. When warm enough, the freeze-stat closes and line power is applied to the the drive. If your AB drive indeed has a similar function built in, just add the heater and make everyone aware that it will take some time before being able to run.

Subvert the dominant paradigm... Think first, then act!

 

[NNG]

I've to add just in Jraef's comments.
The 1336 AB Drives have a different Front-Ends, depending on size: Low HP with Diode Bridges and the Pre-Charge with SCR, while High HP with SCR Bridges and Pre-charge Control, so it's mean that Jraif's idea about pre-charging DC Bus works correctly.
They do not have any low temperature sensors in my experience and the High-temperature sensor failure is the most accurate.
In our drive application for cold temperature packaging we using the internal enclosure heaters to pre-heat the Drive before to start running it.
Krusher, estimate how many watts for heater you need and then run your Drive.
Thanks

 

[jOmega]

No Low Temp Sensor ... ?


I guess it's not possible to use the thermal sensor on the
heatsink to also report LOW temperature ???????

Or is it ?


Oh, and the Low Temp function..... is not an OPERATING limit. It is a STARTING inhibitor.

And as to the comment about low temp and the bus caps, consider that the low temp function doesn't prevent the drive from going thru pre-charge. It prevents the drive from going into run mode from a START command !!!

 

[Krusher]

jOmega, jraef and all,

I took jOmega's advice and contacted Rockwell. They said it would not operate 0c or below as jOmega's post and manual states. Had I read and/or retained better..... I have a small heater in the switch panel and problem is solved.

Thanks for your time and advice!

Best, Roger

 

[jOmega]

Krusher,
Thanks for the feedback.
Glad to have been of service.

jOmega

p.s. Incidentally, ABB's drives also have such a start inhibit based upon low temperature.

 

[jbartos]

Suggestion: Usually, bringing a device from storage at low temperature, e.g. -40C, to at least 0C according to specifications, requires more than checking temperature. There may be ice that may thaw into water. Therefore, some higher temperature that evaporates the moisture is needed. Normally, electrical equipment, e.g. switchgear, panels, etc. use internal heaters.

 

[Krusher]

jOmega,

Well, the reason for my confusion was the fact that the drive showed a high temp fault when it failed to start. I really don't know if this is the proper fault for the ambient temp being below 0C. My bad for not stating this in my original post. Would this fact change any thinking? Being that warming the drive has allowed it to operate, I believe it is an ambient temp thing.

 

[jOmega]

Krusher,
It's been over a decade since I was involved in the Bul. 1336 product and the memory is a bit fuzzy (CRS has set in )

Suggest checking the Rockwell (nee: Allen-Bradley) manual for an explanation of the High Temp Fault. The answer may lie therein. If I get a chance later this morning, I'll look it up.

It just might be that they didn't provide logic to annunciate both the high and low temperature condition.

 

[jOmega]

Krusher:

I checked thru their instruction manual and their Troubleshooting manual.

There is nothing about displaying OverTemp or High Temp fault when temp goes below 32 F ... Also found fault 55 for open temp sensor.... but there was no explanation there either than that of an open temp sensing device.

Once more I would refer you to Steve Spaeth or one of his people at Rockwell Automation in Mequon Wisconsin. Steve's email address previously posted above.

Gary Woltersdorf would be another person to talk to as he has lived with the history of the Bul. 1336 drives... I'm not sure if he's still there or not. You could try G.Woltersdorf@ra.rockwell.com

Kind regards,