Fluke 9011 S+E

6.9 Proportional Band

In a proportional controller such as this, theheater output power is proportional

to the well temperature over a limitedrange of temperaturesaround the

set-point. This range of temperature is called the proportional band. At thebot-

tom of the proportional band, the heater output is 100%. At the top of the pro-

portional band, the heater output is 0 to 100 (hot side)and –100 to 100 (cold

side). Thus, as the temperature rises the heater power is reduced, which conse-

quently tends to lower the temperatureback down. In this way the temperature

is maintained at a fairly constant temperature.

The temperature stability of the well and response time depend on the width of

the proportional band. If the band is too wide, the well temperature deviatesex-

cessively from the set-pointdue to varying external conditions. This is because

the power output changes very little with temperature and the controller cannot

respond very well to changing conditions or noise in the system. If the propor-

tional band is too narrow,the temperature may swing back and forth because

the controller overreacts to temperature variations. Forbest control stability, the

proportional band must be set for the optimum width.

The proportional band width is set at the factoryand printed on the Report of

Calibration. The proportional band width may be altered by theuser if desired

to optimize the control characteristics for a particular application.

The proportional band width is easily adjusted from the frontpanel. The width

may be set to discrete values in degreesC or F depending on the selected units.

The proportional band adjustment is accessed within the secondary menu. Press

“EXIT” while holding down “SET” and then releasing bothto enter the sec-

ondary menu and show the heater power.Then press “SET” to access the pro-

portional band.

S+E Access heater power in secondary menu

9011 Dual-Well Calibrator

User’s Guide

28

Figure 5 Temperature fluctuations at various proportional band settings

Contents

Main Page Table of Contents 7 Digital Communication Interface . . . . . . . . . . . . . . . . 37 8 Test Probe Calibration . . . . . . . . . . . . . . . . . . . . . . 43 Page Figures and Tables 1 Before You Start 1.1 Introduction 1.2 Symbols Used Tabl e1 International Electrical Symbols 2 1.3 Safety Information 1.3.1 WARNINGS Page 1.3.2 CAUTIONS 1.4 Authorized Service Centers Page 2 Specifications and Environmental Conditions 2.1 Specifications -it 2.2 Environmental Conditions 9 2.3 Warranty 3 Quick Start 3.1 Unpacking 3.2 Set-up 3.3 Power 3.4 Setting the Temperature 4 Parts and Controls 4.1 Rear Panel 4.2 Front Panel 4.3 Top Panel 4.4 Constant Temperature Block Assembly 9011 Dual-Well Calibrator 16 Insert A Cold block insert shown (Hot block C insert includes eight 1/4" wells) 5 General Operation 5.1 Setting the Temperature 5.2 Changing Display Units Un= C 6 Controller Operation 6.1 Well Temperature 100.00C 6.2 Temperature Set-point 6.2.1 Programmable Set-points 20 SET Select Setpoint Adjust Setpoint Units C/F Scan On/Off Scan Rate Figure 4 Controller Operation Flow Chart Cold Side Only DO NOT CHANGE THESE VALUES S 6.3 Scan 6.3.1 Scan Control Sc=OFF Sc=On S 6.3.2 Scan Rate Sr=2.0 Sr=3.0 S 6.4 Temperature Display Hold 6.4.1 Switch Status 6.4.2 Scan Hold 6.5 Ramp and Soak Program Menu 20.00C S+U ProG S 6.5.1 Number of Program Set-points Pn=8 E Pf=1 Pf=4 6.5.5 Program Control P=OFF S 6.6 Set-point Resistance 99.222 6.7 Secondary Menu 6.8 Heater Power S+E SEC 12.0P 6.9 Proportional Band S+E SEC 12.0P S ProP 4.1 10.0 S 6.10 Controller Configuration 6.11 Operating Parameters PAr 6.12 High Limit S 6.13 Serial Interface Parameters Page 6.13.4 Linefeed (cold side only) LF LF=On LF=OFF 6.14 Calibration Parameters CAL Page S Page 7 Digital Communication Interface 7.1 Serial Communications 7.1.1 Wiring 7.1.2 Setup Page 7.1.3 Serial Operation 7.2 Interface Commands 40 Tabl e 2 Controller Communications Commands 41 7 Digital Communication Interface Interface Commands Controller Communications Commands continued 42 Controller Communications Commands continued 8 Test Probe Calibration 8.1 Calibrating a Single Probe 8.2 Dry-well Characteristics 8.2.1 Stabilization and Accuracy Page 9 Calibration Procedure 9.1 Calibration Procedure 9.1.1 Calibration Equipment 9.1.2 Calibration Page 10 Maintenance 11 Troubleshooting 11.1 Troubleshooting Problems, Possible Causes, and Solutions 11.2 CE Comments 11.2.1 EMC Directive 11.2.2 Low Voltage Directive (Safety)