Simulate

Do-it-yourself electrical or electronic simulators is not so easy or practical.

Pt100 sensors have some non-linearity so using a potentiometer (variable resistance) won't be accurate.

If you want to just simulate readings at various temperature points, it becomes easier. Just read the resistance with a good and accurate ohmmeter and find the temperature that it represents. For example, if you have a 120Ω resistor, your temperature will be between 51 and 52°C (more like 51.58°C).

You can use a variable resistance to simulate current but, again, accuracy might be an issue. If it's not very important, go ahead.

I have no idea what your no. 3 means. Please elaborate.

Thank you Vulcan. For the Reply.

For the first ones, yes is correct, but it is just to show in the display of the controller how the temp and the pressure can be variate ... nothing else.

For the third point, this box have 3 toroids that can measure Current [A] in each phase for example a motor current consumption. I don't want to connect a motor even if it is small. I just want to create a current consumption in each phase triyng to show how the amps can be move in the display. Using a small circuit i.e. varilight for lamps could be a possibility.

Well then, yes, your ideas will do fine. In fact, I, myself, am a stickler for keeping things simple. Simple but practical, that is. For your purposes, using potentiometers is practical enough.

Hi Paul,

years ago I had a lot to do with RTD-calibration and built a Pt-100 simulator.

There are resistors available with lo tempco and best tolerances readyly manufactured for several temperatures. (You buy them as, e.g. "90.0 deg C - Resistor", which then will be adjusted to the resistance a Pt-100 will have at 90°C)

I recommend to wire them in 4-wire-technic and to use really excellent switches for long-lasting and reliable operation. The switches are as important as the resistors as thermocouple-effects and lowest contact-resistance will influence your measuring results.

Don`t know where you are - I bought my resistors at BURSTER.DE, a company whose meat is to sell calibration equipment.
Those resistors are not cheap as you can imagine - another possibility is to buy a couple of lo-tempco-bread-and-butter-resistors and select them out, this will save some money and waste some time, just depending on what`s your priority.

They have 4-20mA simulators, too.

Regards Uwe

<1. Simulate a PT 100 signal with a variable resistance. Wich is the value for the variable resistance ? >

A PT100 sensor has a resistance of 100Ω at 0degC. So any variable resistor can substitute for the device. http://en.wikipedia.org/wiki/Resistance_thermometer gives the temperature/resistance characteristics, and from the temperatures to be simulated, which only the original poster knows, a suitable variable resistance can be selected.

<2. Simulate a pressure transducer (4-20mA) with a variable resistance.>

Yes, it can be done and it is done. It's amazing how useful a 5K variable resistance and a cheap ammeter can be sometimes.

<3. Simulate a current consumption in 3-Phase.......>

_{No answer posted.}

My (similar) Demo Station had:

1. 68 Ω resistor + 100 Ω potentiometer (pot).

2. Omega Current Source 4-20 mA, but you can built simple electronic circuit with Operational Amplifier where a pot will give you chance to simulate current from 0 to 25 mA or more to show faulty situations. There are many Analog Circuit catalogs.

3. I had 3 * CT (three current transformers) supplied from 3-phase autotransformer (or 3 single phase to simulate non-symmetrical). Regulated Outs from autotransformers were connected to secondary windings of CTs. Primary windings of CTs were shorted to form a source of higher 3-phase currents