Answer / carl_ellis

A DC power supply converts it input, AC line voltage to a
regulated DC voltage output.

A relay coil can be driven by one voltage and its contacts
can operate at a different voltage so a relay coil could
operate at 230Vac, with its contacts switching 24Vdc. But
that's not 'converting' AC to DC; the relay itself requires
that those voltages be supplied to it, it can not 'convert'
AC voltage to DC voltage.

There are linear power supplies and switch mode power
supplies (SMPS).

Relay logic is the name for the use system logic consisting
of discrete relays, switches, timers and counters which are
wired point to point.

Ladder logic is the symbolic representation of the same
elements used in relay logic: relay coils for inputs, relay
contacts for outputs, contacts for switches, timers and
counters in PLC programming.

The ladder representation looks like a ladder with rails and
rungs. The rails are line power rails, the rungs have the
logic elements in parallel or series as needed.

Carl Ellis
Measure First

Answer / sajjad khan

in PLC relay use only switching device'
i think using rectification convert 230 AC to 24 VDC
use 105400 volt PF and diodes and filter copacitor 220uf35 volt copacitor and Ziner Diode 24 volt 2 watt.
it's circuite is very simple and small.

What is the load line in control valve?

1 Answers   IFFCO,

---

Can we measure pressure using differential pressure transmitter? If yes then how?

5 Answers   Reliance,

---

Please tell me details about Sox,Nox,SWAS analyser????

0 Answers   Essar,

---

Can combine control system for Emergency control system (ESD)and Fire & Gas System ( F & G) is possble to built and offer to client? Can such system is as per Norms in India?

0 Answers  

---

how magentic flow tx. vortex flow tx & ultrasonic flow tx works and its prinicle?its callibtration prosedure?

1 Answers  

---

Any body have know try work calculation ???

0 Answers  

---

NAME ANY TWO PHOTO CONDUTIVE MATERIALS?

1 Answers   DVC,

---

If a control valve is hunting means means if we are giving 50% to the cv, the cv will open at 51% then slowly slwoly it will reaches 49% , then it will reaches again 50%, this type of action occured frequntly.. so what to do for solve this problem. The possible cause is in volume booster or positioner's relay.. positioner is double acting .. and make siemens..sipart.The cv is double acting and mounted for anti surge operation, it having 4 nos. volume booster, one sov, one positioner, etc..?

2 Answers   Gujarat Fluorochemicals Limited (GFL), Shell,

---

why orfice is not used for main steam flow calculation

0 Answers   OEG,

---

Explain the difference between mmwc and mmwg?

0 Answers  

---

What is transducer

4 Answers   IFFCO, Jindal,

---

The process variables that need to monitored and controlled are ________, ________, _________ and

1 Answers  

---