Chromalox 2110 Manual de instrucciones - Página 13

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5. Control and Alarm Operation

Control Operation

The 2110 is shipped from the factory with PI (propor-

tional/integral) control. Proportional control actually

determines the percent of heat needed to control the

process. The factory setting for the Proportional Band

is 25°F and the Automatic Reset (Integral) is set at 0.1

repeats/minute. These settings will control many pro-

cesses without any changes to the controller. If the

process is unstable or too sluggish, the Proportional

Band and Automatic Reset can be changed in the

menu configuration.

Tuning PI Control

Adjust Proportional Band - The objective of the pro-

portional band adjustment is to find the proportional

band setting at which the process temperature stabi-

lizes and does not oscillate. If the temperature display

is oscillating, increase the Proportional Band (doubling

the value) until the temperature display has stopped

oscillating. To establish a quick response to control up-

sets, adjust for the smallest band that provides stable

control (does not oscillate). Note: The temperature at

this point may not be at set point, but will be stable.

Adjust Automatic Reset (Integral) - The Automatic

Reset (Integral) automatically removes the offset be-

tween process temperature and set point. If the pro-

cess is too sluggish in approaching set point, double

the automatic reset. Too much automatic reset will

make a process unstable.

Cycle Time - Cycle time setting determines how often

to switch the output to the heater. For example, if the

cycle time is 1 second and the 2110 needs a 75% out-

put, the output will be on for 3/4 of a second and off 1/4

of a second. Units with relay control outputs (R1 or R3)

are shipped with a 30-second cycle time. Units with

solid state relays or solid state relay drives (S0, S1, S2,

or V0) are shipped with a 1-second cycle time.

Alarm Operation (optional)

An alarm relay output is optional on the 2110. An alarm

can help protect the process when a too high or too

low temperature occurs.

High Alarm: This alarm is a high absolute alarm that

actuates when the process temperature is equal to or

greater than the alarm set point. For example, if the

high alarm set point is 500°F, the alarm will always ac-

tuate when the process temperature reaches 500°F.

Low Alarm: The low absolute alarm actuates when the

process temperature is equal to or less than the alarm

set point. The low alarm features a power-up inhibit to

prevent undesirable alarms during process start up. Af-

ter the unit reaches control set point, the low alarm will

respond.

Alarm Dead Band: The alarm relay de-energizes (re-

sets) when the temperature crosses out of the alarm

dead band. For example, if the high alarm is set to

500°F and the alarm dead band is 5°F, the alarm condi-

tion will not reset until the process temperature reach-

es 495°F.

To enable the alarm relay, select either high or low alarm

type and set the alarm set point. An alarm condition is

indicated when the Alarm light to the left of the display

illuminates. Alarm type, set point, and dead band are

selectable through the user configuration interface.