Frequently Asked Questions



Is it possible to extend the cable of temperature probes and, if yes, what measures must be taken?
 
  • Yes, it's possible to extend the cable within the limits appearing on the table shown here below:
    PTC1000, 2 wires x0.35 sqmm: up to 20 m without compensation
    NTC, 2 wires x0.35 sqmm: up to 20 m without compensation
    Pt100, 3 wires x0.24 sqmm: self compensation
    TC: self compensating special cable
    Transmitter 0..1V: up to 10 m
    Cables must never run together with leads carrying large currents.


When is it necessary to use screened cable for the connections to the serial line or for the probes?
 
  • The screened cable reduces the electromagnetic interference influence over low intensity signals. It's therefore advisable for industrial environments where there are large currents or where there are radio frequency sources (transmitters, RF equipment etc.)


How is it possible to distinguish the probes on multi-input instruments?
 
  • On instruments like the LCD15, LF28 etc. the probes are equivalent with each other and become different only after they have been placed in the plant: air, evaporator etc. It's however important that a probe, after it's been placed, is connected to its own input (air -> T1; evaporator -> T2 etc.). The difference in colour or marking appearing on the cable has the only purpose of making its identification easier.


On the instrument the inscription "Output.. 8(3)A 240 Vac" appears. What is its meaning?
 
  • Conventionally this inscription is used to indicate the maximum switchable currents. For example, with what we indicated above we mean that for a load working at 240Vac the maximum current is 8 Amp. if purely resistive and 3 Amp. If inductive, as in the case of an electrical motor.


How many switchings can a relay perform safely?
 
  • The life of a relay depends on several factors such as: the connected load, either resistive or inductive, the supply voltage and how frequently the load is switched. The currents appearing on our controllers indicate the maximum switchable currents with a normal duty cycle for a period of at least 5 years. For example, with "normal duty" for a refrigeration thermostat, we mean a switching frequency of about 10 cycles/hour.
    Lower currents or lower switching frequency will cause a proportional extension of this lifetime.


What is the difference between 'CE' mark and other marks like VDE - UL - IMQ etc.?
 
  • With the 'CE' mark the manufacturer states - under his own liability - that the product conforms to the present EU directives. These directives provide the minimum requirements for safety, electromagnetic emission and immunity, toxicity and for all the other aspects necessary to a product to operate when it's used according to its instruction sheet. The other marks are stamped when the manufacturer is the licensee of a mark registered by a National Institution that - under its own liability - declares that a product has been manufactured in compliance with the laws regarding electrical safety.


Are instruments usable immediately after purchase or do they require preliminary settings?
 
  • The instruments that we produce are delivered with a configuration thought for a generic usage. It's therefore ALWAYS necessary to read the enclosed instruction sheet explaining how the unit operates and the meaning of the configuration parameters. Then, before plant startup, please check ALL parameters and if necessary modify them in order to obtain the necessary adaptation of the unit to the system connected.


Why does the instrument controlling my refrigerator switch off the compressor at a temperature different from the setpoint?
 
  • In many of our instruments there are several adjustments that generate this phenomenon, among these the slowdown parameter and the display offset. Such settings have got the aim to simulate the product temperature on the display, although the probe measures the air temperature. In some cases, as for example in the CDC123, there's also a third probe designed for the display and it's different from the thermostat probe.


Is it possible to power more instruments by means of a single transformer?
 
  • In many cases, more instruments are connected together to the same electrical circuits, such as a serial line, digital inputs, active probes (transmitters) etc. In this case, the connection to a single transformer would therefore create a hidden circuit hindering correct operation. On these grounds, before connecting the instruments it's necessary to make sure that such hidden circuits can't be created in any way and that the transformer has got a suitable power.





Compressor control refrigeration control temperature control - LAE ELECTRONIC