Alternator Malfunctions

[haroldc_gtmc@sbcglobal.net]

This serious problem with the Lookout "Alternator" object occurs when the object sees unexpected remote pump starts. Typically the alternator coupled through a neutral zone and tower level transducer in the HMI controls the pumps without any problem. Water drops, pump turns on, water rises pump turns off... etc... When a pump is manually put in "hand" on its controls cabinet, an "unexpected start" alarm appears in Lookout, this too is normal.

The problem is that this might start another pump in the system even though we are not calling for water. To make thinks even worse, that pump will not shut off at my pump off level setting. I have to ramp my lead and lag settings up and down to get the alternator back in sync... I could program my own alternator should not have to... Help would be appreciated.

[Ryan.S]

I think it's a normal behavior. For example, if you set "command" to 2, and stop one of the running device, it will try to find another device to run. So another pump will start after you put a running pump in "hand".
If you only have 3 pumps, one is in "hand". The other  2 pumps will continuously running. Because no other pumps can be switched to.

Here is an example for your reference.

[rfoote]

Ryan

Yeah, but the pumps that the "alternator" DOES run should respond to the neutralzone's settings and shut off when the shutoff level is reached for any pumps still in Auto.

The original poster is saying that the neutralzone doesn't work anymore if a pump gets put in hand. If that is true, that is a pretty serious defect.

I remember trying the "alternator" object way back in the V3.8 and before period and it didn't work correctly then either. I ended up putting the pump logic in the site PLC.

I never tried it after that.

[bkinard@kinardcontrolsyst]

This may be the same problem that I am having although I could not find what was causing it. An alternator object that had been working for a while had stopped responding. All of the logic was the same. I ended up creating a new alternator object with the same logic and deleting the older one. After that, it seemed to work just like it always has. This has happened SEVERAL times. I have learned not to use the alternator object on critical pump scenerios.

In addition to the problem with the object failing, I have also found that if an HOA switch is turned into the OFF position, the object has to have a complete cycle before it gets put back into rotation with a lead/lag setup. I have tried tying the "advance" command of the object to a pushbutton, but it does nothing. If that isnt correct, then how does the "advance" command need to be configured?

[Ryan.S]

rfoote,

The original problem was fixed in Lookout 6.1. There was something wrong in the logic.

Hope the problem you met in 3.8 is the same one. 

[Ryan.S]

Brian,

Connect the pushbutton to Alternator.advance, just like the process I attached.

For example, all 4 devices are in Auto, command is 1. Device 1 is on now. If you click pushbutton, device1 will be off, another device will be on.

I also tried to turn one device into OFF from Auto or Hand. If it's on and I turn it to OFF, it will be off immediately, and be disconnected. Another device will be on.

So, I think this object is working properly. I'm not sure what acutally you saw in your process.

[haroldc_gtmc@sbcglobal.net]

I have now purchased 6.1.  The alternator has the same issues.  It can not be trusted.  Simple things like a user turning a Lookout HOA switch to off after a pump is started by the alternator can crash the application.   A remote site power outage or communication failure should not take down a water system. I have also had crashes make the application unusable. That's right, the application can't be started.  Additionally 6.1 will crash intermittently during development.  I find myself backing up every 5 mins just to get ahead of the crashes that will come.  I have shut down every vista scheduler, firewall, defender etc... Does not help. What really can make you crazy is trying to get the alternator back in sync.  When the application is up and running its amazingly dependable. I know I need to work on my own alternator.  Its features are very useful... Max Runtime, Total Runtime based pump rotation, Comm fail actions, failure to start actions, HOA connections etc... would require a lot of written code. 

[Ryan.S]

We fixed a bug in Alternator in Lookout 6.2, but I think we probably need to build a fix for the 6.1 object.

When you input incorrect format of the Alternator parameters, Alternator still accepts it, but Lookout may crashes.

For example, the "Device response time" is DD:HH:MM:SS. If you input "01:11:11:60", Alternator object will accept, but it may crash Lookout. The correct is "01:11:12:00". HH, MM, SS are from 0 to 59.

Please check the parameters you set. Or you can upload the process to ftp://ftp.ni.com/incoming and let me check.

If you cannot open the process in Lookout, you can edit .lks file in text editor. Find the Alternator object and modify the paramters.

[haroldc_gtmc@sbcglobal.net · Accepted solution]

Thanks Ryan for your input.  

I was also not aware that the a connection to the "response" writable member in the Alternator Connections is not required.  This seems to be the item that was crashing my application.  I assumed that the Alternator expected a response and that is not the case. By not using these connections my problems where resolved.   A simple expression written to alarm and advance the alternator in the case a pump fails to start (I check for water flow) gives my application the safety factor it needs. 

I have renewed faith in this program.