frequency inverters to controll flow rates
frequency inverters to controll flow rates
(OP)
Instead of using control valves in order to control the flow I intend to use Frequency inverters to regulate the motor speed of a centrifugal pump (2.2kW)
With this type of controll I had quiet good experience in the past.
Now my Question: The FI Inverters I intend to use are Siemens Micromasters, they will be used on a test rig with lots of meassuring devices, mainly for temperature, flow and pressure.
Is there any danger that the signals are interfered by the frequency Inverter. What would be your recommendations is it better to shield the inverters in a metal panel or is it o.k. to mount the without enclosure?
:)
With this type of controll I had quiet good experience in the past.
Now my Question: The FI Inverters I intend to use are Siemens Micromasters, they will be used on a test rig with lots of meassuring devices, mainly for temperature, flow and pressure.
Is there any danger that the signals are interfered by the frequency Inverter. What would be your recommendations is it better to shield the inverters in a metal panel or is it o.k. to mount the without enclosure?
:)





RE: frequency inverters to controll flow rates
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RE: frequency inverters to controll flow rates
RE: frequency inverters to controll flow rates
Only one stupid Question, what does PWM and VFD stand for?
One other think, All my signals are 4 to 20mA except for the temperature sensors which are T-Type thermocouples and 4 wire PT-100. The cables of all instrumens are shielded is there any issue with the temperature sensors?
The sensors are powered in general by 24V or 110V supply Voltage, does a frequency inverter effect this voltages in any adverse way.
One last thing, the noise of these Frequency inverters is there any health issue associated with this?
thanks
:)
RE: frequency inverters to controll flow rates
VFD - Variable Frequency Drive. The means by which the drive varies the speed of what is essentially a fixed speed motor. Usually taken to be synonymous with VSD (Variable Speed Drive) although some people will argue that the latter has a broader meaning covering mechanical and other electro-magnetic types of drive.
If you follow good installation practice there should not be any problems with either a thermocouple or RTD. Pay attention to the grounding of screens and shields, both on the instruments and on the power circuit. Use twisted pairs / triads for the instrument circuits and maintain segregation from the power circuit.
Your power supplies should not be adversely affected if they are of good quality and installed correctly.
There are no recognised health hazards caused by electrical noise from a VFD. Maybe on a very large drives older design you might get a sound level where PPE becomes necessary due to audible noise.
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If we learn from our mistakes I'm getting a great education!
RE: frequency inverters to controll flow rates
"Stray Voltage" has been well documented as causing health problems with dairy cattle. Excessive stray voltage at a dairy can cause reductions in milk production, mastitis of the udder, loss of unborn calves, sore feet and other problems.
The dose response curve and replication (50 or more cows per herd) makes it obvious. With humans, each one of us is viewed in isolation. There has been extreme reluctance to examine electrical exposure via plumbing, ground currents, dirty power on wires or any other source. People are much more likely to be treated symptom by symptom, illness by illness.
While the human health effects of exposure to electrical ground currents have gotten little media attention, that is not because they are non-existent. Electrical ground currents are pretty conclusively linked to an increase in the risk of childhood leukemia. The high frequencies that pollute our electricity and cause the electrical ground currents have been linked to increased blood glucose levels, multiple sclerosis symptoms, asthma, allergies, migraines, chronic fatigue syndrome and an assortment of other symptoms.
RE: frequency inverters to controll flow rates
Please cite references for this. I haven't seen anything resembling consensus on this side of the pond to support these claims, only scaremongering by minority interest groups who only acknowledge results of studies which support their agenda and ignore those which don't. Granted there are SOME studies which suggest a link between EM fields and leukemia and other illnesses, and others which show there to be no link at all. Hardly conclusive is it?
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If we learn from our mistakes I'm getting a great education!
RE: frequency inverters to controll flow rates
http://www.electricalpollution.com/
RE: frequency inverters to controll flow rates
It is my understanding that electromagnetic related "illnesses" are a recognized workers health hazard in both Sweden and Russia, elligible for medical treatment including paid recouperation time. In Sweden, it is also my understanding that the offending equipment must be corrected or removed. I am interested to know if true.
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"We can't solve problems by using the same kind of thinking we used when we created them." -Albert Einstein
RE: frequency inverters to controll flow rates
What might be of interest is the following report
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which does acknowledge that some people may suffer from a variety of other ailments due to exposure to EM radiation.
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If we learn from our mistakes I'm getting a great education!
RE: frequency inverters to controll flow rates
RE: frequency inverters to controll flow rates
Of course it doesn't - it was published by the Government! More seriously, I think there is a lot more research needed to understand the mechanisms through which EM radiation interacts with living things before we can make any meaningful judgement.
I have heard of the problems with cows before. It's not so much stray voltage as stray current which is flowing in the mass of earth rather than in a line or neutral conductor. The current directly passes through the body because the cow forms a parallel path with the ground. I guess cows are susceptible because of their size - greater potential difference between their front and back legs compared to a smaller animal - and propensity to be found in very damp conditions giving a good connection to earth.
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If we learn from our mistakes I'm getting a great education!
RE: frequency inverters to controll flow rates
http://web.jrc.ec.europa.eu/emf-net/
http://virtualpipeline.spaces.msn.com
"We can't solve problems by using the same kind of thinking we used when we created them." -Albert Einstein