Vacuum Pressure Transmitter

VVFD is an undefined acronym.

How about video/voice/fax/data

for the first, I don't see why not. You just have to find the proper equipment for the application. So long as there is a difference in pressure and vacuum is an absence of pressure,, you can use a differential pressure transmitter. or am I way off base here?

1. If you put one of the difference inputs on vacuum and seal it, you get a direct vacuum transducer.

2. If you leave it open (=ambient pressure) you have to measure the ambient pressure, too, to get an idea of the vaccuum (indirect transducer).
Uwe

VVFD is veriable voltagae veriable frequency drive.

I believe that all models of AC variable frequency drives being marketed at this time include variable voltage, because motor design requires that the voltage and frequency remain in a (nearly) fixed ratio. Thus, a motor with a name plate rating of 480V at 60Hz can be safely operated at 400V and 50Hz, with derating only for horsepower output because of the slower speed. The algorithms which are used to form the drive output choose spacings between the pulses as well as pulse widths to increase or decrease the voltage as the frequency increases or decreases, in addition to changing the voltage continuously to create the sinusoidal waveform.

If you are speaking of a change in drive input voltage, this is much more of a problem, because their setup parameters usually require the internal DC voltage bus to remain between a high and low limit or else the drive will fault out. With some brands of drives and with factory assistance, one may be able to change internal parameters to reduce these settings (to correspond to a reduced input voltage for the same piece of equipment), but you generally cannot increase them because the electronic components would have dielectric failure.

-JMM

Guest,

Sure! We utilize a differential pressure transmitter to determine our vacuum pressure in a vacuum furnace application. Check out the following link. This is what we use to read from ATM to full vacuum. Very reliable.

http://www.omega.com/pptst/Px305.html

Hope this helps.