Watlow EZ-ZONE ST User Manual download pdf (Page 21)

Warning:

Use National Electric (NEC)

or other country-specific

standard wiring and safety

practices when wiring and

connecting this controller to

a power source and to elec-

trical sensors or peripheral

devices. Failure to do so may

result in damage to equip-

ment and property, and/or

injury or loss of life.

NOTE: To prevent ground

loops, isolation needs to be

maintained from input to out-

put when using switched DC

or analog process outputs.

CAUTION: Always mount the

controller with the heat-sink

fins aligned vertically.

NOTE: Terminals L4 and

A1 on the limit connector

are jumpered at the factory

to complete the contactor

circuit. Additional switches

may be wired in series to the

terminals.

WARNING: If high voltage is

applied to a low-voltage con-

troller, irreversible damage

will occur.

Watlow EZ-ZONE

ST • 19 • Chapter 2 Install and Wire

Input 2 Thermocouple

Slot A

• 20 kΩ maximum source resistance

• >20 MΩ input impedance

• 3 microampere open-sensor detection

• Thermocouples are polarity sensitive. The negative lead (usually

red) must be connected to S2.

• To reduce errors, the extension wire for thermocouples must be

of the same alloy as the thermocouple.

ST _ L - _ _ _ _ - _ _ _ _ (limit)

Input 2 RTD

2-wire

Slot A

3-wire

Slot A

• platinum, 100 and 1,000 Ω @ 0°C

• calibration to DIN curve (0.00385 Ω/Ω/°C)

• 20 Ω maximum lead resistance

• RTD excitation current of 0.09 mA typical. Each

ohm of lead resistance may affect the reading by

0.03°C.

• For 3-wire RTDs, the S1 lead (usually white) must

be connected to R2.

• For best accuracy use a 3-wire RTD to compensate

for lead-length resistance. All three lead wires must

have the same resistance.

ST _ L - _ _ _ _ - _ _ _ _ (limit)

Input 2 Process

volts

Slot A

amperes

Slot A

• 0 to 20 mA @ 100 Ω input impedance

• 0 to 10VÎ (dc) @ 20 kΩ input impedance

• 0 to 50 mVÎ (dc) @ 20 kΩ input impedance

• scalable

ST _ L - _ _ _ _ - _ _ _ _ (limit)

1 2 ... 16 17 18 19 20 21 22 23 24 25 26 ... 96 97

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Watlow EZ-ZONE ST User Manual Page 21

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