Answer / rejith prasad

In 4 to 20mA system, min. value is 4mA n max. value is 20mA and if there is a wire breakage, the value comes down to 0mA. Which means wire brekage can easily b detected. While in 0 to 20mA system, min. value is 0mA n wire breakage value will also be 0mA...... that is the reason y we use 4 to 20mA rather than 0 to 20mA.......

Answer / simon marshall

The 4-20mA loop can be used with active sensors. The
minimum current of 4 mA powers the sensor. (The sensor then
must act as a variable current sink through its supply
terminals varying the current it draws in proportion to the
quantity it is sensing such as the millivolts or so from a
thermocouple, for a 4-20mA temperature gauge.) I do not
know how the powering current of 4mA was arrived at. The
specifications allow a range of maximum voltages for the
loop to operate on and the sensor power can then be
satisfied in different designs by altering the minimum
voltgage drop on the device. The item powering the loop
then must also be designed to measure the current drawn in
the loop but read out on a display with the transfer
funtion zero to full scale deflection = 4mA to 20mA

How to convert design gray to binary code?

0 Answers  

---

Explain the operation of 3φ bridge inverter for 1800 degree mode of operation with aid of relevant phase and line voltage waveforms?

0 Answers  

---

bank exam related............

1 Answers   Banking,

---

how many maximum signaling link can be created between two gsm switches and why?

0 Answers   Ericsson,

---

What you mean by setup box?

3 Answers  

---

What is memristor? How many modes it works? What is its advantage?

0 Answers  

---

why do we use 4to20mA not a 0to20mA?

2 Answers  

---

please somebody who have asked questions related to electronic and communication eng siemens 2010-2012 post here

0 Answers   Siemens,

---

Define why series inductor and l-section filters cannot be used with half-wave rectifiers?

0 Answers  

---

interface an 8-pin switch with 8085 microprocessor located at 0AAH and LEDs at port 55H, draw the circuit diagram. Write down a program to read the switches and do the following: > if the parity of the switch is odd, start counting upward until it reaches 0FFH. > if the parity of the switch is even, start counting downwards until it reaches 00H.

0 Answers  

---

Explain the difference between a multiplexer and encoder? Also what is the between demultiplexer and decoder?

0 Answers  

---

Differentiate between static and dynamic resistance of a diode.

0 Answers  

---