Analog Signal 0 - 10Vdc, Input/Output - PLC Configration:
Analog
Input Signal 0-10vdc is universally using control signal. It is used in various
simple application in PLC as Input or Output analog signals to drive any kind
of process variables.
In
input cases, this signal used in PLC to monitor or configure the process active
variable with respect to decided the output readings. In output cases, this
signal delivered from PLC to drive the decided output readings. This 0-10vdc
cannot be used for long distance due to rise in resistance in cables causes the
drop voltage losses its accuracy.
Further, this voltage is converted into digital logic signal by PLC which can be easily intercepted by decided output reading to drive the process equipment with respect to input signal.
All analog signals are susceptible
to electrical interference, and a 0-10V signal is certainly no exception.
Devices such as motors, relays, and “noisy” power supplies can induce voltages
in to signal lines that can degrade the 0-10V sensor signal. Also, a 0-10V
signal is susceptible to voltage drops caused by wire resistance, especially
over long cable runs.
Galvanic Isolation is possible with this signal to prevent possible damage to the PLC by Electro Magnetic Force or Dynamic Static Charges.
A 4-20 mA or 0-20 mA signal, on the
other hand, offers increased immunity to both electrical interference and
signal loss over long cable runs. And most newer industrial controllers will
accept current signals.
As an added bonus, a 4-20 mA signal provides inherent
error condition detection since the signal, even at its lowest value, is still
active. Even at the extreme low end, or “zero” position, the sensor is still
providing a 4 mA signal. If the value ever goes to 0 mA, something is wrong.
The same can not be said for a 0-10V sensor. Zero volts could mean zero
position, or it could mean that your sensor has ceased to function.
In some cases, 4-20 mA sensors can be slightly more costly
compared to 0-10V sensors. But the cost difference is becoming increasingly
smaller as more sensor types incorporate current-output capability.
In power electronics, like D.C Drives and A.C Drives and Soft starters and Heating Control, Fan Control Circuits deliveres proposational value of opto isolated 0-10vdc to monitor configrable speed/load current/frequency data to M.C (moving coil- indicating intruments) instruments or Digital Instruments.
The same signal is used in input use, to drive the above said power electronics units 0-10vdc remote drive signal or through 0-10kohm potentiometer to 0-10vdc converter.
0-10vdc signal will consume maximum 10mA current. Further the listed points are characterised for this kind of signal,
- If the input signal wire get short it delivers the unexpected full output.
- If the input signal wire get opens it delivers the zero output.
- If 10vdc wire gets grounded the output will hang and no output will be deliver.
- By using Screen cable, distortion due to harmonic or E.M.F can be prevented, but still considerable mV loss will appear
- In order to change the direction of rotation in A.C or D.C Drives units, the -ve 10vdc is applied to the separate input results the motor will run at reverse direction without need of logic contact to reverse the motor direction.
APPLICAION USED 0-10v SIGNAL:
1. Pressure Transducer: This kind of transducer delivers 0-10v proposational to desired water pressure or air pressure or any gas pressure. The span and zero adjustment can be made by adjusting inbuilt potentiometer to control the required output.
2. Flow Transducer: This kind of transducer used to monitor the liquid flow or gas flow etc to deliver the 0-10v signal proposational to flow rate. This flow rate transducer used to control the desired liquied flow in various applications.
