Alarm; see thermocouple open alarm below.) – Watlow Series D8 User Manual

Page 112

Chapter 4: Operation and Setup

Series D8 User’s Guide

Watlow Anafaze

Doc. 0600-3120-2000

Thermocouple Open Alarm

The thermocouple open alarm occurs if the controller detects

a break in a thermocouple or its leads.
If a thermocouple open alarm occurs, the controller switches

to manual mode. The output level is determined as follows:
•

If the Open T/C ht/cl out average parameter in the Output

menu is set to on, then the controller sets the output pow-

er to an average of the recent output.

•

If the Open T/C ht/cl out average parameter is set to off,

then the controller sets the output to the level indicated

by the Sensor fail heat/cool output parameter in the Out-
put

menu.

Thermocouple Reversed Alarm

The thermocouple reversed alarm occurs if the temperature

goes in the opposite direction and to the opposite side of am-

bient temperature than expected—for example, a loop is heat-

ing and the measured temperature drops below the ambient

temperature.
The thermocouple reversed alarm is enabled by default. If

false alarms occur in your application, you can disable the

alarm by setting the Reversed T/C detect parameter to off. See

Thermocouple Short Alarm

The thermocouple short alarm occurs if the process power is

on and the temperature does not rise or fall as expected. To en-

able the thermocouple short alarm, you must do the following:
•

Choose a digital input for the TC short alarm parameter

in the Global setup menu.

•

Connect the digital input to a device that connects the in-

put to controller common when the process power is on.

RTD Open and RTD Fail Alarms

The RTD open alarm occurs if the controller detects that the

positive RTD lead is broken or disconnected.
The RTD fail alarm occurs if the controller detects any of the

following conditions:
•

negative lead is broken or disconnected

•

common lead is broken or disconnected

•

positive and negative leads are shorted

•

positive and common leads are shorted

•

positive, negative and common leads are shorted