help with current monitoring setup

[electric101]

I've had some issues with a vacuum pump tripping but I believe we have resolved them... in dealing with it I found that all the other motors in that area have current monitoring setup on the HMI where it displays the amps for each motor... except the one im working on. I have some free analog inputs on my controllogix PLC but I'm not sure what else I might need? I've seen some current transformers online but the ones I was looking at seemed to require some other software (power monitor for allen Bradley) if anyone could give me any ideas on what I need it would be most helpful.

thanks,

 

[CLXlifestyle]

I like these guys.

http://www.veris.com/Category/Current-spcMonitoring/Current-spcTransducer.aspx

 

[OkiePC]

I have used the UPC from Load Controls:
http://loadcontrols.com/products/

 

[Gene Bond]

I use these all the time: http://www.automationdirect.com/adc...ltage_Sensors_(AC_-a-_DC)/Current_Transducers

 

[Peter Laing]

The Weidmuller 'picopak' #991624 is a DIN rail mounted 0-5A AC to 4-20Ma converter. They're self powered, easy to use, inexpensive, and reliable. Simply wire a 0-5A CT to the input terminals, supply loop power (24VDC) and wire the 4-20mA output to your PLC input.

 

[electric101]

just FYI the motor consistently pulls 38amps per leg and the breaker that was tripping was a 50amp. I'm wanting to be able to monitor it on the HMI and maybe build in a latching bit to catch exactly when it trips.

 

[GTUnit]

Check the type of breaker in the panel. Make sure its rated for motor loads. All breakers are Not the same regardless of the AMP rating printed on the front.

It also feels like overkill trying to use a PLC to find your problem. If you want to monitor running current, ok, but to diagnose this problem you can use the MAX setting on your current clamp meter.

Monitor the motor when it starts. How often does it start and how long between starts?

 

[Ravioli]

For Troubleshooting / logging motor current I like Fluke's Bluetooth based "Fluke Connect" Series. You're not limited to having an available PLC input, and they are relatively cheap at $200 each.

I like the logging Fluke a3001-fc It has a flexible current clamp that can fit over thick 350MCM cables, or in tight spaces, and you don't have to break the circuit. The meter can be left to log, for the better part of 2 weeks on a set of 4 AA batteries (with Bluetooth shut off). You can also install the meter in an enclosed panel, and view the readings wirelessly with a PC (or a phone).

To download I recommend the Fluke PC3000-FC Adapter You cannot use your PC's bluetooth adapter.

Beware they have a Zig-bee based "CNX" line that is incompatible, and inferior.

I will also be honest. The meters are built to Fluke's usual excellent rugged standard, but the software is beyond horrendous. I'm lucky if I can connect in the field, and even when I unplug the meter, bring it to the office, set it next to the adapter, and shut off all neighboring 2.4Ghz Wifi or Bluetooth devices it is slow, and unreliable to download.

The Phone app is even worse. It it beyond "Beyond horrendously" horrible. In addition to having to register for a Fluke account, it fails on downloads continuously. It will also completely abort the download when the maintenance manager calls you to ask how you are making out on the breakdown. They make the app out to be something where the engineer at home can be twirling his mustache and connect with the sparky's phone at the plant and tell him what to do. In reality you can be the engineer at the plant trying to download the data, and the app will fail and crash.

I will have to check the sampling rate, but within each period it will show a min, max, and average current. Throw on three meters and you have each phase. If you're lucky you have some logged data from the PLC to compare against.

 

[redbarron55]

What kind of overloads do you have on the starter?
The overloads should trip if the motor is overloaded and not the breaker.
If the breaker is tripping then it is not setup correctly.
The overloads mimic the heat buildup in the motor and can be set for class 10, 20, or 30.
The class 10 etc is the number of seconds the motor can pull 600 X the FLA rating to start.
If the vacuum pump takes a long time to start then a higher class rating would be required.
You did not state if the motor was tripping on start or long time running.
You could mimic an overload circuit in the PLC, but that is the job of the starter overload.
I have done this in the case of a Chipper motor in a Chip N Saw, but mostly since the old starter had ancient oil filled dampers for short time and long time trip and they were bad and we did not have the money to change out the system.
The restarting of the 400 hp motors caused more heating than the temporary overloads.
Fix the starter and size the breaker properly with the correct type.

 

[BurrisLabs]

I also think you've got a problem in the sizing of your motor/protection because a 50amp breaker on a running load of 38amp is pretty tight during starting. Look at the full load current (FLA) on the motor's data plate. I like to use Schneider's guide:
http://www.schneider-electric.us/sites/us/en/support/product-support-resources/software-and-calculators/calculators-and-online-tools/nema-motor-data-calculator.page

 

[electric101]

when I found the drawings I saw that the original breaker should have been a 63amp but was at some point replaced with a 50amp. this vacuum motor circuit is a star delta starter that starts on a timer in the plc in star mode... when the timer expires and speed is reached it swaps to delta connections.... I thought that the changeover might have been the problem so I increased the time from3 sec to 4sec but it turned out that the contactors making the circuit were the problem... i could barely touch one of them and it trip the breaker during running operation.... I've replaced and its been fine since. thanks everyone for all your help, I've learned a ton and I'm going to try to get a current logging meter.

thanks again.