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 installation and commissioning of (fat & sat) of power plant dcs ? this question keeps in desirable conditions of one company .

0 Answers  

---

what is the importance of CV in the control valves? how it is calculated?

0 Answers  

---

i have one tank of 500mm height, which is in under vacuum of 735 mmHg, I want measure level of the same using DPT , SO WHAT WILL BE THE URV & LRV, DENSITY OF THE TANK FLUID IS 0.95. is there necessary to fill the LP side with fluid.

7 Answers  

---

WHAT IS MEANT BY SUPERVISORY CONTROL?

3 Answers  

---

wht is mean by dpt(differential pressure transmitter)

1 Answers  

---

cascade controller is feed back or feed forward or both

4 Answers  

---

What is standard procedure of manual mapping in Radar type level transmitter?

0 Answers  

---

please anyone suggest me some good intools training institutes with their place and contact nos.

1 Answers   ABB, Thermax,

---

Basics Instrumentation Question

1 Answers   Advantek Fuel Systems,

---

whatis virtual instrumention?

5 Answers  

---

what diffrence b/w plc s7200,300,400

0 Answers   IFFCO, Reliance,

---

What is the difference between a Extension cable and a copnesating cable.Where can we use compensating cable. Is anywhere compensating cable are used for mv transmission to the indicator.

1 Answers  

---