Toshiba L5232 6F8A0917 , 8.5.2 Zero Offset Adjustment

6F8A0917

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120

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8.5.2 Zero Offset Adjustment

This function is used to perform zero adjustment simply by comparing the output of the flowmeter

with other process value without stopping the process flow.

If zero adjustment can be performed with still water condition, it is not necessary to set this adjustment

value.

How to calculate the zero offset value

Zero offset is performed by setting the adjustment value.

The adjustment value can be obtained by the following equation:

Adjustment value (%) = {(Actual flow rate) − (LF232 measured value)}

* Calculate the value in percent of the setting range of Range 1.

(See the example below.)

(Example)

Flow rate Value in percent of the set span

Actual flow rate obtained from

other process value 10.0 m3/min 50.0 %

LF232 measured value 10.5 m3/min 52.5 %

Zero offset adjustment value −2.5 %

(If zero offset adjustment value is set to −2.5 %, the output of LF232 is shifted by

−2.5% and 50.0 % output can be obtained.)

The zero offset adjustment value can be set within the range of ±0.410ft/s (0.125 m/s) (±1.25% of

the maximum range 32.8ft/s (10 m/s))

Note: If you perform still water zero adjustment, zero offset adjustment value becomes zero.

Checking the zero offset adjustment value

Proceed as follows to check the zero offset adjustment value.

Switch operation Display example Description

O1: MANUAL ZERO

+002.5 %

Select O1: MANUAL ZERO from the setting item selection

menu.

The currently set zero offset adjustment value appears.

O1: MANUAL ZERO Returns to the menu of setting item selection.

Contents

Main 6F8A0917 Electromagnetic Flowmeter Converter LF232 Type INSTRUCTION MANUAL NOTICE 2 SAFETY PRECAUTIONS Color explanation 3 SAFETY PRECAUTIONS (continued) Safety Precautions for Installation and Wiring 4 SAFETY PRECAUTIONS (continued) Safety Precautions for Maintenance and Inspection Usage limitation 6F8A0917 Handling Precautions 6F8A0917 Handling Precautions (continued) 6F8A0917 Table of Contents 6F8A0917 8 Page 1. Product Inspection and Storage 1.1 Product Inspection 1.2 Storage 11 2. Overview 12 3. Names of Parts Appearance Page Page 15 4. Installation Cautionary notes on installation 6F8A0917 4.1 Cautionary Notes on Selecting the Installation Location 4.2 How to Install the Converter Page 19 5. Wiring Cautionary notes on wiring 5.1 Installation Cables 5.2 External Connections 5.1 External Wiring Connection Diagram 6F8A0917 5.3 Cautionary Notes on Wiring 5.3.2 Cautionary Notes on Wiring between Instruments and Converter 6F8A0917 23 5.4 Wiring Method 5.4.1 Terminal Treatment of Cables Page 6F8A0917 25 Power cable, current output cable and digital I/O cables 5.4.2 Cable Connection Page 6F8A0917 5.4.3 Grounding Figure 5.9 (b) Wiring between Detector and Converter (when grounding for detector is difficult) Figure 5.10 Detector Grounding Method 5.5 Digital I/O Connections 6F8A0917 30 5.6 Cautionary Notes on Replacing Converter Wiring 6F8A0917 5.6.2 Combination with an Existing Detector (for Large Meter Size) Figure 5.12 How to Connect an Adjusting Capacitor 6F8A0917 Wirering Please be careful. Table 5.4 Cable connection mouth specification comparison list (Partially filled pipes type) 6. Operation Page 7. Display and Controls 7.1 Names and Functions of Display and Controls Page Functions of each switch (Measurement mode) Enabled to change the setting value (Setting mode) ( (Menu display) (Setting mode) 7.2 Display Format Measured value display format Page 42 Notes on total flow value display (5) Percent display (6) Custom unit display 7.3 Basic Operations Page Page 6F8A0917 46 7.3.2 Setting Mode Operation Page 48 Checking or changing the setting values ( ) 6F8A0917 49 7.3.3 Password Input 50 Example of password input (mode selection: SET and password: 123) 6F8A0917 7.3.4 Totalizer Operation 52 Example of totalizer operation 6F8A0917 53 7.3.5 Maintenance Menu 7.4 Setting Menu List Return to measurement mode 8. Parameter Settings / Adjustment 8.1 Parameter Setting Items 6F8A0917 56 8.2 Parameters Check / Change 8.2.1 Exciting Current Value Checking the exciting current value Proceed as follows to check or change the exciting current value. 57 Changing the exciting current value 6F8A0917 8.2.2 Meter Size 59 Changing the meter size of the detector 6F8A0917 60 8.2.3 Exciting Frequency Checking the exciting frequency 61 Changing the setting value for exciting frequency. The following is an example to change the exciting frequency from 24Hz to 12Hz. 6F8A0917 62 8.2.4 Flow Direction Checking the flow direction. 63 Changing the flow direction. 6F8A0917 64 8.2.5 Password Setting 65 Changing the password 6F8A0917 66 8.2.6 Normal Indicating Unit 67 Checking the normal indicating unit 68 Changing the flow direction for total flow Note 1: The flow direction for total flow is displayed cyclically as follows: 6F8A0917 69 8.2.7 Custom Unit 70 Checking the coefficient of custom unit Proceed as follows to check the coefficient of custom unit. 71 Checking the unit string of custom unit Proceed as follows to check the unit string of custom unit. 6F8A0917 72 8.2.8 Span Value 73 Span value Page Page 76 Changing the range type 77 Changing the span value 78 Changing the hysteresis 6F8A0917 8.2.9 Damping Constant 80 Changing the damping constant The following is an example to show how to change the damping constant from 0.5 sec to 10 sec. 6F8A0917 8.2.10 Low Cutoff value 82 Changing the low cutoff value The following is an example to show how to change the low cutoff value from 1.0% to 3.0%. 6F8A0917 83 8.2.11 Current Output Setting Used When an Alarm Occurs Checking the current output value used when an alarm occurs 84 Changing the current output value used when an alarm occurs 6F8A0917 85 8.2.12 Display low cut On/Off Checking whether the display low cut is On or Off 86 Changing the display low cut On/Off setting. 6F8A0917 87 8.2.13 Output Low Limit Setting Checking the output low limit value setting. 88 Changing the output low limit value setting. 6F8A0917 89 8.2.14 Digital I/O Function Digital output state (only when alarm output is set) 6F8A0917 90 Digital Input Function Level setting for digital input control signal (for totalizer control only) 91 Checking each setting for digital I/O 92 Changing each setting for digital I/O 6F8A0917 93 8.2.15 Count Rate (Pulse Rate) and Pulse Width 94 Pulse width 95 Checking the count rate and pulse width Changing the count rate 96 Changing the pulse width mode setting The following is an example to change the pulse width mode setting from 2:MANUAL to 1:AUTO. 97 Changing the pulse width The following is an example to change the pulse width from 100ms to 250ms. 6F8A0917 98 8.2.16 Preset Counter 99 Checking the preset counter setting Changing the preset count value 100 Changing the preset output function 6F8A0917 101 8.2.17 Flow Rate High/Low limit Alarm High/low limit value 102 Checking the high/low limit alarm setting 103 Changing the high/low limit alarm On/Off 104 Changing the high/low limit value 6F8A0917 105 8.2.18 Fluid Empty Alarm Setting the fluid empty alarm 106 Changing the fluid empty alarm On/Off setting. 6F8A0917 8.2.19 Self-Diagnosis Function 108 Alarm output factor setting Checking the self-diagnosis alarm setting 109 Changing the self-diagnosis function setting 6F8A0917 110 8.2.20 Rate-of-Change Limit Value and Control Time 111 Changing the rate-of-change limit setting 8.3 Initial Settings When Shipped from the Factory Initial settings used when shipped from the factory unless otherwise specified are shown below. Page 114 8.4 Fixed Value Output (Loop Check) Page 116 Changing the fixed output function 117 Changing the fixed output constant 6F8A0917 8.5 Zero Adjustment 8.5.1 Still Water Zero Adjustment Note2 Note2 Page 6F8A0917 120 8.5.2 Zero Offset Adjustment 121 Changing the zero offset adjustment value 9. Mag-Prover Calibration 9.1 Calibration Items 6F8A0917 123 9.2 Converter Check / Calibration Checking the zero point Calibrating the zero point 6F8A0917 9.2.2 50% Flow Rate Calibration 6F8A0917 125 9.2.3 100% Flow Rate Calibration (Span Calibration) 6F8A0917 9.2.4 Checking the Exciting Current Value 10. Function Description 128 10.1 Digital I/O Specifications 10.2 Totalizer and Pulse Output Page 131 Totalizer operation using digital input signals 10.3 Multi-Range Functions 133 Output performance when multiple ranges are used (2) Forward and reverse directions (internal automatic switching), 2 ranges Output when switched from Reverse to Forward direction Output when switched from Forward to Reverse direction Page (4) Forward and reverse directions (external signal switching), 2 ranges Works even if the range output is not used. Output when switched from Reverse to Forward direction Output when switched from Forward to Reverse direction Page 138 10.4 Flow Rate High/Low Limit Alarm Output Flow rate high/low limit alarm output performance Page Page 141 10.5 Fluid Empty Alarm Output 10.6 Preset Counter Output Function 143 Preset counter output performance Page Page 10.7 Remote Still Water Zero Adjustment 10.8 Remote Selection of Fixed Value Output 10.9 Converter Error Alarm Output 11. Communications Function 11.1 Connection with the HHT terminal Page 11.2 Procedure for Communication with HHT 11.3 Cautionary Notes on Communications 153 12. Diagnosis and Alarms 12.1 Diagnostic messages High/low limit alarm 154 Process error alarm Fluid empty alarm 155 Self-diagnosis error 12.2 Output When an Error or Alarm Occurs 157 13. Maintenance and Inspection 13.1 Maintenance Page 6F8A0917 13.2 Troubleshooting 13.2.1 Flow rate is not indicated 6F8A0917 13.2.2 Flow rate indication is not correct 6F8A0917 13.2.3 Flow rate indication is not stable 6F8A0917 13.2.4 When switch operation is unable 14. Principle of Operation 164 15. Specifications 15.1 Specifications Page 166 Page Page 15.2 Model Number Table LF232*A, LF232*B Converter model number table LF232*F (for partially filled pipes detectors) Converter model number table 16. Outline Drawing