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FAQs

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Q)

What is an IP rating?

A)

This is a protection rating. Please see the FAQ section entitled "general topics" for further information

Q)

Can PTC and NTC probes be extended?

A)

PTC and NTC probes can be extended but a few precautions should be observed as follows: (1) the maximum advisable distance is approximately 100 metres. (2) always use good quality low resistance cable with a large cross sectional area. This will minimize any additional resistance from being imparted, which could effect a controller's accuracy.(3) on long runs, use screened cable and only earth one end of the screen. (4) do not run probe cables alongside power cables.

Q)

What is the main difference between PTC & NTC probes?

A)

PTC - resistance increases as temperature increases.
NTC - resistance increases as temperature decreases.

NTC probes work at higher resistance values than PTC.

Typical sensor resistances at C are:

Q)

Are there probes that are more accurate than PTC or NTC?

A)

PT100 probes can be used for greater accuracy, but only with a controller calibrated to accept this probe type.

Q)

What if PTC or NTC probes do not cover the required temperature range?

A)

Consider PT100, Ni100 or thermocouples type K, J or S. Some of these can cover temperatures as wide as -70 to +500°c but you must use a suitable controller.

Q)

I need a 4 stage controller but I want to be able to assign individual stages as either heating or cooling.

A)

Most 4 stage controllers can provide 4 steps of either heating or cooling but not both at the same time. However, some have change over relays that can be wired individually for heating or cooling, for example, the Saginomiya FSE range

Q)

I want to control head pressure using a fan speed or step control. Should I choose an instrument that controls on pressure or temperature?

A)

Pressure sensing controls (e.g. the Saginomiya RGE) are generally more expensive but are more accurate and will respond much faster. Temperature sensing controls (e.g. Eliwell or Dixell) are often less expensive but are less accurate and will respond more slowly.

Q)

I need to control on a temperature averaged between two points.

A)

It is necessary to arrange 4 probes (in 2 pairs) to form a "Wheatstone Bridge". We can advise on the exact wiring arrangements.

Q)

I have a number of systems and must avoid them defrosting together. How do I ensure separation of defrosts?

A)

For up to 4 systems use controllers with built in interval timers, with a parameter that delays the start of defrosts. Typically, this parameter will be adjustable from 0 to 59 minutes, so with a maximum of 4 controllers, defrosts could have a minimum guaranteed separation of 15 minutes. The parameter's setting must be in non-volatile memory to ensure that defrosts will remain separated even if power is interrupted.
For more than 4 systems use controllers that have "Real Time Clocks" built in. These allow you to set precise times of day for defrost to occur so each controller can have different defrost times. Alternatively consider Centralized scheduling of defrosts using a temperature monitoring & alarm system. These consist of a central monitoring & alarm panel or PC, which is connected to all the controllers by a network cable. A signal from the central unit can initiate defrosts by individual controllers to avoid simultaneous defrosting.
We can select the appropriate controllers on request.

Q)

I'm trying to adjust a parameter setting on an electronic controller and it won't go beyond a certain value.

A)

Electronic controllers use logic programming which prevents conflicts between parameters. Assuming that the value you are trying to alter is not at the limit of its adjustment, there is probably another parameter setting that is in conflict. Consider which parameters may conflict and check their settings. E.g. you are trying to lower the Upper Set Point Limit to + 5°c but it will not go lower than + 10°C. Check the Set Point, if it is set at + 10°c the problem can be fixed by lowering the set point before setting the upper set point limit.

Q)

A controller is flashing an alarm message. What does it mean?

A)

Typical alarm messages and their causes are as follows:

Q)

Is there a programming guide available for Eliwell and Dixell controls?

A)

We can offer printed programming guides for the most popular instruments:

• Eliwell EWPC series (also includes EWTB100 & EWDR975)
• Eliwell EWPX series
• Dixell XR, XT, XC and Prime series
• Dixell Universal-R

Please e-mail info@thermofrostcryo.co.uk and request the specific guide that you need.

The following listed guides are also available for downloading from this site in Adobe Acrobat Reader format:

• Dixell XR, XT, XC and Prime series (387KB, Acrobat Reader .pdf file)
• Dixell Universal-R installation & operating instructions (319KB, Acrobat Reader .pdf file)
• Eliwell EWPC series (196KB, Acrobat Reader .pdf file)
• Eliwell I series (48KB, Acrobat Reader .pdf file)

If you do not have Acrobat Reader it is also available as a free download

Information is also available on the Eliwell and Dixell web sites.

Q)

Is there a multi-purpose control for use as a service replacement?

A)

The Dixell Universal-R can be used to replace most of the 32 x 74mm format panel mounted controls from LAE, Carel, SAE, Eliwell, Intek, Every and Teddington. It can function as a thermostat, thermostat with off-cycle defrost, thermostat with time intiated and time or temperature terminated defrost, or thermostat with time intiated and time or temperature terminated defrost plus fan delay. It also includes audible/visual high & low temperature alarms and an alarm relay output.

It works with either 1 or 2 probes as required, and is compatible with both PTC and NTC probes. It operates on a 12v AC power supply. Programming is quick and simple and we offer either a printed guide or you can download it as an Acrobat Reader (.pdf) file:

• Dixell Universal-R installation & operating instructions (319KB, Acrobat Reader .pdf file)

If you do not have Acrobat Reader it is also available as a free download

For the printed guide please e-mail info@thermofrostcryo.co.uk

Q)

Do you have any training courses for electronic products?

A)

Yes. For further information please download details (13K Acrobat Reader file)