m&m control systems

[scuba]

We operate a 550ton nh3 system controlled by a m&m operating system cira - 1987 with some updates installed around 1993. We have been notified by m&m that our main control boards,expander boards and touch panels are no longer availiable. We our in the process of trying to convince manegement to update our system,but I think we are talking to deaf ears. The problem is we are experiencing many nuisance alarms. Examples are suden oil pressure fluctuations both high and low, discharge pressure that are way out of parameters and others. We have changed temperature and pressure transducers and have calibrated them. We have also verified there is no actual system fluctuations by installing pressure gages into the system. The system might run fine for days then start alarming for no apparent reason. Just checking to see if anyone else has had these problems and if they were able to correct them.

[NH3LVR]

I do not have experience with the M&M panel as most of my work has been on FES and Frick.
That being said, older panels do get to be a little cranky.
I have seen these problems occur because of a failing power supply. Check the outputs of the power supply with a good voltmeter and if they are withing the specs turn the meter to AC and read that. If the AC component is over 1/2 or 1% of the AC reading you can have problems. (Others are more expert at the Electronics end than I, and maybe could give more accurate figures)
I once had a problem with a erratic electrode chiller in the High Tech end. I hooked up a Laboratory Power supply in place of the 5 Volt DC and we were up and running.

[Magoo]

I had similar problems with a M&M variant ( local regional ), the regulated power supply to computer processor was the main issue, the 5vdc supply is critical +/- 0.2 vdc., processor influenced by noises in power supply as well, so add power filters to control suppliy and snubbers to all internal contactors.( 240vac or your controls voltage ) The last two years were trouble free motoring so-to-speak
The whole thing becomes a nightmare and you start chasing shadows.
One system was replaced with a A&B PLC system and panel veiw., at a horrendous cost, but client could not handle production stoppages, which cost even more everytime system stopped. that could be the basis to approach your management people. M& M are bound to have a retro-fit system available.
magoo

[Magoo]

Scuba
Something you could try is to get a technician to set up an osciliscope, and monitor the 5vdc system to processor, the osciliscope will trace all power influences that will effect processor.
Another thought is go through system PCB's and re-terminate each connection, ie., clean and refix each input to processor board. Slight corrossion can dramaticly influence anolgue inputs at strangest times for no obvious reason.
Just an added thought. Magoo

[scuba]

Thanks for the replys NH3LVR and Magoo,I will check the regulated power supplies on monday and see what happens.

[nh3wizard]

We operate a 550ton nh3 system controlled by a m&m operating system cira - 1987 with some updates installed around 1993. We have been notified by m&m that our main control boards,expander boards and touch panels are no longer availiable. We our in the process of trying to convince manegement to update our system,but I think we are talking to deaf ears. The problem is we are experiencing many nuisance alarms. Examples are suden oil pressure fluctuations both high and low, discharge pressure that are way out of parameters and others. We have changed temperature and pressure transducers and have calibrated them. We have also verified there is no actual system fluctuations by installing pressure gages into the system. The system might run fine for days then start alarming for no apparent reason. Just checking to see if anyone else has had these problems and if they were able to correct them.

We have several of our facility's have M&M systems; and what you might have a grounding issue on one of your transducers causing the fluctuations, and just changing transducer will not fix the problem you have to change the the connecting wire and transducer. M&M should have guided you in that direction.

[scuba]

we checked the grounding per m&m instructions, checked all the connections and changed the power supply and have not had any problems so far. Thanks for the replys.

[nh3wizard]

we checked the grounding per m&m instructions, checked all the connections and changed the power supply and have not had any problems so far. Thanks for the replys.

Was it the power supply that was causing the problem?

[scuba]

yes it was the power supply we found no other problems. although the output voltage was o.k. at the time of the last check before changing it ,the power supply was running about 15 degrees hotter than the others.

[ammonia tec]

I have a rxf frick thats with new connections and power packs still shuting down on i/o com failures.
with correct voltage to sub boards checked sensors b-rate ,relays.. the board are old micro plus.its always everybody about being cheap and not investing in upgrades which a 1980 exxcel program outdated!. were to a point f-it as a service respon. to inform the customer and go on,,. and then they want to protest the bill for the repeated about 3x a month. couple of hours each time. most of all mfg suggest needed upgrade,after serveral tips and brain storming form many people.

[ref717]

The best solution here is to replace your operating system with new a new SCADA system. Operating any ammonia system big or small is no joke. Convince the big bosses that lives are at stake here and Safety First should be everybody's concern and thus prevent accidents.

[Magoo]

Check the initial post date people, 12 months out of sinc.,

[ammonia tec]

join in late but it caught my eye