Tips & Tricks
Here you will find instructions on how to set up and operate our products, as well as troubleshooting tips.
Only 3.1 mm DIN Rail per channel
What is meant by standard signals?
In an industrial environment measuring signals are frequently converted for conveyance via the power lines. The standard signals have a fixed maximum value and are therefore especially easy to continue processing. The inputs of programmable logic controllers (PLC) or process control systems are frequently dimensioned for these standard signals.
What is live-zero?
Live-zero raises the identification rate of a plant's failures and hence increases operating reliability. Here the measuring value zero is not transmitted as a standard signal of the variable zero; instead it obtains an offset. For current loops this offset is fixed at 4 mA.
If there is line breakage or the transmitter fails, the result is a signal at 0 mA, but because measuring starts at 4 mA, the failure or line breakage can be detected unmistakably.
Customary live-zero standard signals are:
- 4 - 20 mA
- 2 - 10 mA
- 2 - 10 V
- 1 - 5 V
To what extent can I override the measuring range?
Within certain bounds the measuring range between, for example 4 and 20 mA can be exceeded or undercut. Normally a range from 3.8 to 20.5 mA should be able to reach the maximum output level. This is what NAMUR defines in its recommendation NE 43. Below and above these values there are voltage ranges for signalisations, typically 3.6 mA or 22 mA.
What is 3-port isolation?
3-port isolation comprises isolation distances between the input circuit and the output circuit and auxiliary energy. The supply of auxiliary energy is neither located on the input potential nor on the output potential; it is an independent galvanically-separated circuit.
The structure of the isolation amplifier with 3-port isolation affords reliable protection against erroneous measurements owing to earth problems and parasitic voltages.
How do I configure the desired measuring range?
Our universal isolation amplifiers can cover a multitude of measuring ranges. To enable you to select your desired measuring range, these amplifiers have a row of small switches (DIP switches); the interaction between input and output are defined by how they are combined.
You will find a table with the feasible switch combinations on the type plate or on the other side of the isolator. Set all the switches marked with a dot in the table to ON.
What is safe isolation?
Safe isolation is the mutual isolation of electrical circuits. This separation can be created by means of double insulation, basic insulation with an additional electric protection shield or reinforced insulation.
Safe isolation to protect maintenance personnel and the downstream devices against inadmissibly high voltage is described in the EN 61140 standard.
How high is the test voltage?
The test voltage for the individual devices is specified in the technical data. In most cases the test voltage for DRAGO signal converters is between 1.5 kV and 2.5 kV (at 50 Hz, all circuits in against each other).
In the High Functionality series we also offer select types of loop-powered isolators, standard signal, multipurpose and shunt isolation amplifiers with 4 kV test voltage.
Connecting the fill-level measuring transducer to a PLC
Measuring transducers, especially 2-wire measuring transducers often have the measuring signal available as current in the 4 to 20 mA range. However, for the analog input card of a PLC, input voltages are required within the 0 to 10 V range or 0 to 5 V.
Ideally, a standard signal isolation amplifier complements your system in two ways at once:
- The isolation amplifier converts the current-measuring signal into the appropriate voltage signal
- Thanks to the isolation amplifier you additionally have the galvanic isolation of the inputs
Comparison of measuring distances with potentiometers
Errors and signal distortion, which may arise from sensor errors and/or divergent measurements by the measuring transducer, are easy to compensate using the potentiometers on the front of the isolation amplifier.
For example, based on the installation geometry, sensors can deliver a slightly falsified measured value. Using the potentiometers to compensate the ZERO and SPAN measured distances, this kind of divergence in the percent range can be corrected, enabling the downstream devices, e.g. a PLC to obtain a correct measured value.
Conversion into another standard signal
Our standard signal isolation amplifiers support different standard signals at the input and output. With the aid of the small switches (DIP switches) you can configure the desired combination of input and output signal. A table showing the optional combinations is to be found on the type plate or on the label on the opposite side.
In the Tiny-Snap series you must specify the desired combination of input and output variables already at the time of ordering, because - owing to the small design no setting is offered on the amplifier.
Do you have further questions?
Then ask us your question by email or call our hotline at +49 30 40 998-222.