We need to monitor the current profile of several AC servomotors, in order to detect mechanical issues in the driven machinery. The drives we use have no connectivity options, so that is not an option. Should be no big deal anyway, except for the response time of the AC current transducer that...
Follow-up:
I made a test today on one of the fans, at fixed speed (56 Hz), checking the plenum pressure under various conditions:
The whole machine (10 molds) running: 58"H2O
machine stopped (0 molds): 54"H2O
1 mold running: 56"H2O
2 molds running: 58"H2O
3 molds running: 59"H2O
4 or more...
thanks again for your comments. In the glass container manufacturing industry, maintaining stable mold cooling regardless of the day/night temperature swings has always been an issue, but the truth is that I´ve never seen a serious study or modelling of the effect of temperature swings on the...
Yep, if all or most of the dampers are open, pressure and temperature behave as expected. If none or only one damper is open, pressure begins to drop and temperature rises sharply.
It has always been that way, on every machine, in fact this setup up is standard in all glass bottle manufacturing plants, but only on that machine have we noticed that behaviour of "surging" (or whatever it is) causing that pressure decrease/temperature increase when airflow decreases.
In a glas bottle machine, airflow is directed from the fan's outlet plenum into pass-through openings in the cast iron bottle molds. The machine can have up to 10 molds working at the same time, and each mold has its own automatic damper that opens only when the corresponding mold is actually...
I understand your point Drazen, we use fan speed to control outlet pressure (we don't have outlet flow measurement) and thus airflow, which makes the actual cooling job. But we were wondering if perhaps there was a point where the temperature increase due to the increased pressure would...
Our glass container manufacturing plant has several 350HP VFD-controlled fans for bottle cooling. They normally run close to full speed (60Hz), since the outlet pressure setpoint is normally set to 60"H2O, the fan´s rated pressure at rated airflow. However, since we would like to have the...
What can I use to fill the 1/4" gap between the tip of an RTD and its thermowell? something that can be readily available anywhere, like grease, etc..? it is installed on an air duct, temperatures are low, 60 degC max. thanks for your advise.
Actually the meter is downstream of 2 aftercoolers and a drier, however the air is almost always saturated when we measure relative humidity, since we have a less than optimal installed capacity of driers for our compressors.
The issue here is to find out if thermal type flowmeters are adequate...
We aquired thermal mass flowmeters to measure compressor outlet flows (in the 70 psig, 8000-10,000 SCFM range), but we get very erratic readings from the instruments. I suspect it has something to do with moisture content (sometimes air is completely saturated), but the manufacturer mentions...
We still use a lot of synchronous motors in our plant, driven by VFDs in V/Hz mode, with sizes ranging from 3 to 10 HP approximately. Sometimes a single VFD runs 2 or 3 motors, so the VFDs are usually oversized to allow starting individual motors at normal speed without overcurrent trips.
Since...
Thanks for your comment. I really can't get rid of the VFD, because we do need to modulate fan speed in certain situations. We will install an inverter duty motor to diminish the probability of premature motor failure, but I will still try to find out why these guy heats up much more than its...
Thanks for your comments. Frame temperature is measured either with thermal imaging camera or raytek type infrared thermometers, and temperature normally hovers somewhere around above 95 degC, much hotter than all the rest of the similar sized motors, either with VFD or DOL driven, which...
