Answer / naveed iqbal

actually in proximaty probes inside used PNP tanasistor.so
transistor baising supply need - dc voltage.

Answer / chandrakant sahu

There is PNP type transistor used in ocsilator and also ti keep minimum interference negative voltage is suitable for this

Answer / waleedmahmoud

The basic reason is that the power supply is -24 VDC. So
since the supply voltage is negative the output voltage
will be as well.

IRD at one time made prox probes with a positive supply and
as a result a positive output.

Way back in the 50's uncle Don Bently made a design
decision to use a negative supply voltage (back then it
was -18 VDC rather than -24 VDc in the modern device) in
his circuit. This decision has stuck and is now even
included in the API standards

Positive are also there for example.

Metrix 5465F is -ve gap voltage

Metrix 5465E is +ve gap volatge

It does not make much of a difference wether you use
positive or negetive voltages. It is -ve because Bently
started with the design of -ve and now we stick to -ve.

Answer / md. rizwan

Because we measure the negative voltage in vibration system.

in DCS or PLC we can not put all ai or di,there is calculation through which we can accomodate certain no of digital and analog signal.I need to know that calculation

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We do have a problem in the company that is one PT connected to PlC which is mean 1 out of 1 in PLC system we do have the PAHH is 55 mbar and PALL 8 mbar with a timer of 15 sec for the PAHH the problem started when PAHH goes more than the set point which is 55 it reached up to 71 but due to timer doesn't trip . We force it and we checked everything nothing there . We replaced the transmitter problem still there the reading goes more than the 55 bar the range for transmitte is 0- 60 mbar . So we did loop check , aculaizing valve , wiring all are okay . What the possible causes for this ???

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How will you test a transistor with a multimeter?

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What is the purpose of RS Networks

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