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Sunday, February 08, 2015

Electrical Control Panel Wiring

Just like rackmounts hold big instruments or computers, control panels small or big have to hold DIN Instruments, switches and annunciators to make it easy for the operator. The maintenance work also is simple from the backside. It can be kept near the machinery which it controls.

Some Control panels go into Control Rooms at a distance away or at a greater height from the shop floor. This way they can monitor and give instructions while managing a larger process like processing of chemicals and at the same time safeguarding the instrumentation and computers with controlled environments.

Electrical Control Panel Wiring

Some of the pdf circuits are not easy to read, some have errors, this is mainly due to the importing of schematics from an older ORCAD Dos Version. I have corrected some circuits, some are to be checked. Also some circuits were not corrected after they were drawn by New Learners, as i wanted them to document what they learnt and familiarize with computers, Some did a good job. This section has no electronic parts, so you can figure out the diagrams.

Some example circuits of panels here Electrical Control Panel Wiring

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Saturday, February 07, 2015

Process Control Instrumentation

This is a generic or standard controller for any type of process. Shown here is a temperature controller.

The STC1000 could be used for Ovens or furnaces, liquid baths, heating or environment chambers. It has a single analog input and an analog or relay output.
Temperature Controller

Process Control Instrumentation Section Updated

Analog inputs could be like 4-20 mA, thermocouple or RTD. Analog outputs can be 0-10 V for a thyristor drive, SSR drive output or potential free contacts of a relay to operate external 3 phase contacters.

The closed loop control could be On-Off or Time-Proportional. It was known as digital temperature indicating controller. Sometimes it would be used just as a Alarm or in a Trip circuit for protecting a system, when a uP or uC based PID controller fails.

This is used in the processing of plastics, rubber, metals and in chemical plants too. Here is a checklist that was made for helping its fabrication. You can see the limitations in which we manufactured these products. An optimum quality was evolved, defined by a user's affordability of the product.

Wednesday, February 04, 2015

Process Control Circuits for Automation

These are the circuits and boards of a Mini Temperature Transmitter for a Platinum hundred ohms temperature Sensor.

Industrial Process Control Circuits has been updated.

3 Wire Transmitter

Circuits in process control
The customer wanted a two wire system, this needs low power opamps which were ten times the price. If this transmitter works at 3mA it could have been two wire. Those parts were in short supply and the budget of customer was low. So i made it with regular opamps but three wire. The customer was satisfied as he got a cost effective solution. But now the situation of markets and products are different.

If you need to transmit the temperature from a high voltage area or toxic environment. You will need to hermetically seal the transmitters, convert the Voltage to frequency, frequency to IR LED flashes or RF. This can be then remotely monitored. Then the transmitter has to be battery-solar operated, low power too. ICL7135 is a simple solution. It has a serial output that can be used to Drive IR Leds. Remotely sense these flashes in a Micro-controller and you have a reading. You may be able to use optic-fibers too. Where volatile liquids are present so that the risks of sparks can be eliminated.

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