Athena 2000 Series Instrukcja obsługi - Strona 7

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Thermocouple

Wiring Circuits

RTD Wiring

Circuits

NOTE: RTDs

tend to be shock

sensitive and

require extra care

in handling and

installation

Thermocouple

Placement

Use thermocouple and extension wire that conforms to the

appropriate thermocouple type specified on the serial number

tag. In thermocouple circuits, the negative lead is colored red.

Extension wires must be of sufficient size so that on long runs

the thermocouple circuit resistance does not exceed 100

ohms.

Do not run thermocouple leads in the same conduit as the

power lines. If shielded thermocouple wire is used, terminate

the shield only at the controller end using the corner screw

provided for that purpose.

Standard Thermocouples

I.S.A. Type

(U.S.A.)

The 2002 and 3220 units are designed for 100 ohm platinum

RTDs. Two-wire RTDs are connected to terminals -1 and -2

with a jumper connecting 2 to 3. Keep leads short and use

heavy gauge copper extension wires if necessary, to minimize

lead resistance. For long runs 3-wire RTD should be used and

wire gauge should be sufficient that resistance does not

exceed 10 ohms.

DO NOT RUN RTD LEADS IN THE SAME CONDUIT AS POWER LINES.

If shielded RTD wire is used, terminate the shield only at the

controller end, using the corner screw provided for that pur-

pose.

Proper thermocouple placement can eliminate many prob-

lems in the system. The probe should be placed so that it can

detect any temperature change with little thermal lag. In a

process that requires fairly constant heat output, the probe

should be placed close to the heater. In processes where the

heat demand is variable, the probe should be close to the

work area. Some experimenting with probe location can often

provide optimum results.

In a bath process, the addition of a stirrer will help to eliminate

lags. Since the thermocouple is basically a point measuring

device, putting more than one thermocouple in parallel will

provide an average temperature reading and produce better

results in air-heated processes.

Materials

Iron-Constantan (I/C)

Chromel-Alumel (C/A)

Copper-Constantan

Color Code

White (+)/Red(-)

Yellow (+)/Red (-)

Blue (+)/Red (-)