RKI Instruments AC-7400 Operator's Manual
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RKI Instruments AC-7400 Operator's Manual

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AC-7400 Gas Monitor
Operator's Manual
Part Number: 71-0551
Revision: P5
Released: 6/27/24
RKI Instruments, Inc.
www.rkiinstruments.com

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Summary of Contents for RKI Instruments AC-7400

  • Page 1 AC-7400 Gas Monitor Operator’s Manual Part Number: 71-0551 Revision: P5 Released: 6/27/24 RKI Instruments, Inc. www.rkiinstruments.com...
  • Page 2 Product Warranty RKI Instruments, Inc. (Manufacturer) warrants its products to be free of defects in workmanship and materials—under normal use and service—for one year from the date of purchase from the manufacturer or from the product's authorized reseller. The manufacturer is not liable (under this warranty) if its testing and examination disclose that the alleged defect in the product does not exist or was caused by the purchaser's (or any third party's) misuse, neglect, or improper installation, testing or calibrations.

  • Page 3: Table Of Contents

    Mounting the AC-7400 Gas Monitor ........
  • Page 4 AC-7412 (12 Channel) Register Map ......... . . 47 4 • AC-7400 Gas Monitor Operator’s Manual...

  • Page 5: Chapter 1: Introduction

    AC-7400. About the AC-7400 Gas Monitor The AC-7400 is an eight or twelve channel gas monitor that functions as a transmission controller. The AC-7400 monitors toxic, combustible, and oxygen gas levels in ambient air by receiving and displaying 4-20mA signals from up to twelve wired sensor assemblies.

  • Page 6: Specifications

    Specifications Table 1 lists specifications for the AC-7400. Table 1: AC-7400 Specifications 110/240V ~ Input Voltage 12 - 35 V AC-7408 Alone • 300 mA at 24 VDC • 60 mA at 115 VAC Current Draw, 8-Channel Version AC-7408 with Powered Accessories and Connected Detectors •...

  • Page 7: Chapter 2: Description

    Chapter 2: Description Front Panel Figure 1: Front Panel AC-7400 Gas Monitor Operator’s Manual Chapter 2: Description • 7...

  • Page 8: Boards

    Boards Figure 2: Terminal Board Figure 3: Sensor Board 8 • Chapter 2: Description AC-7400 Gas Monitor Operator’s Manual...

  • Page 9: Internal Components

    Internal Components Figure 4: Internal Components AC-7400 Gas Monitor Operator’s Manual Chapter 2: Description • 9...

  • Page 10: Chapter 3: Installation

    2. Close and latch the housing door. 3. Prepare the selected mounting site as required to mount the AC-7400. It should be mounted at eye level (4 1/2 to 5 feet from the floor). Refer to Figure 5 for the outline and mounting dimensions.

  • Page 11: Wiring The Ac-7400 Gas Monitor

    Connecting a DC Power Source NOTE: AC or DC power can be used to power the AC-7400. If you are using AC power as the primary power source, go to the next section, “Connecting an AC Power Source”.
  • Page 12 9. If desired, connect an Earth Ground wire (green) to the terminal marked “EGND” (required for surge suppression). Figure 6: DC Wiring 10. Close the Front Panel. 11. Screw in the thumb-screws. 12. Close the enclosure box. 13. Clamp down the enclosure latches. 12 • Chapter 3: Installation AC-7400 Gas Monitor Operator’s Manual...
  • Page 13 Connecting an AC Power Source NOTE: AC or DC power can be used to power the AC-7400. If you are using DC power as the primary power source, go to the previous section, “Connecting a DC Power Source”. WARNING: Verify that the power source is unplugged or turned off before you continue with this procedure.
  • Page 14 • Connect a ground wire from the AC power source to the power supply’s “EG” terminal. Figure 7: AC Wiring 6. Close the Front Panel. 7. Screw in the thumb-screws. 8. Close the enclosure box. 9. Clamp down the enclosure latches. 14 • Chapter 3: Installation AC-7400 Gas Monitor Operator’s Manual...
  • Page 15 3. Open the Front Panel so that the back of the Terminal Board is exposed. 4. Install an appropriately rated cable bushing or conduit in the right-hand conduit hub on the bottom of the AC-7400 housing. 5. Guide the Modbus wires in conduit through the right-hand conduit hub.
  • Page 16 3. Open the Front Panel so that the back of the Terminal Board is exposed. 4. Install an appropriately rated cable bushing or conduit in the right-hand conduit hub on the bottom of the AC-7400 housing. 5. Guide the wires in conduit through the right-hand conduit hub.
  • Page 17 12. Clamp down the enclosure latches. Connecting 4-20 mA Sensor Assemblies The AC-7400 allows up to 8 (one sensor board installed) or 12 (two sensor boards installed) 4-20 mA sensor assemblies to be monitored. 1. Open the enclosure box to expose the Front Panel.
  • Page 18 Connect the sensor assembly’s signal (green) wire to the terminal labeled “4-20 mA”. c. Connect the sensor assembly’s neutral (black) wire to the terminal labeled “GND”. Figure 10: Sensor Wiring, Sensors 1 - 4 18 • Chapter 3: Installation AC-7400 Gas Monitor Operator’s Manual...
  • Page 19 Figure 11: Sensor Wiring, Sensors 5 - 8 Figure 12: Sensor Wiring, Sensors 9 - 12 AC-7400 Gas Monitor Operator’s Manual Chapter 3: Installation • 19...
  • Page 20 Connect the “GND” terminal on Sensor Board 1 to the “GND” terminal on the Terminal Board’s Modbus In block. f. Connect the “B” terminal on Sensor Board 1 to the “B” terminal on the Terminal Board’s Modbus In block. 20 • Chapter 3: Installation AC-7400 Gas Monitor Operator’s Manual...
  • Page 21 Figure 14: Wiring Communication for Sensor Board(s) 10. Close the Front Panel. 11. Screw in the thumb-screws. 12. Close the enclosure box. 13. Clamp down the enclosure latches. AC-7400 Gas Monitor Operator’s Manual Chapter 3: Installation • 21...
  • Page 22 Relay Wiring The AC-7400 has four relays. Each of the four relays may be setup as Normally Open (NO) or Normally Closed (NC). See page 37 for more explanation about relay actuation. NOTE: If installed, the strobe is factory wired to the Relay 1 terminals and the horn is factory wired to the Relay 2 terminals.
  • Page 23 6. Connect the external power source’s “+ (H)” terminal to the COM terminal on the relay terminal block. Figure 15: Relay Wiring AC-7400 Gas Monitor Operator’s Manual Chapter 3: Installation • 23...

  • Page 24: Chapter 4: Startup And Operation

    CAUTION: The internal components can be static sensitive. Use caution when opening the enclosure and handling internal components. Once power is supplied to the AC-7400—by being plugged into an AC outlet or by being wired to a DC power supply—the display screen and LEDs will illuminate.

  • Page 25: Normal Operating Mode

    5. Clamp down the enclosure latches. Alarm Conditions If the gas reading for a channel reaches an alarm setpoint, that alarm type appears in the “ALM” section of the display. AC-7400 Gas Monitor Operator’s Manual Chapter 4: Startup and Operation • 25...
  • Page 26 A Fault condition is occurring on the monitor STATUS blue Normal Operating Mode 1. Press and release RESET/ESC to clear an alarm indication once the alarm condition has cleared. 26 • Chapter 4: Startup and Operation AC-7400 Gas Monitor Operator’s Manual...

  • Page 27: Chapter 5: Setup Mode

    NOTE: To view system information, scroll up from channel 8 (or 12) or down from channel 1. 2. Press MENU (Next). 3. Channel On/Off: Press ADD or SUB to change the state of the channel to On or Off. 4. Press MENU (Next). AC-7400 Gas Monitor Operator’s Manual Chapter 5: Setup Mode • 27...
  • Page 28 • 1 decimal: Scale 100 or less • 0 decimal: Scale greater than 100 (the Set # of Decimals option will not show up in this case). 10. Press MENU (Next). 28 • Chapter 5: Setup Mode AC-7400 Gas Monitor Operator’s Manual...

  • Page 29: Relay Settings

    7. Relay Latch/Auto Reset: Press ADD or SUB to manipulate the relay's Latching/Auto Resetting status. 8. Press MENU (Next). 9. Repeat Step 1 through Step 8 for the remaining relays. AC-7400 Gas Monitor Operator’s Manual Chapter 5: Setup Mode • 29...

  • Page 30: View System Information

    1. Press ESC at any time to exit Setup Mode. 2. Close the enclosure box. 3. Screw in the thumb-screws. 4. Clamp down the enclosure latches. NOTE: The monitor will automatically exit Setup Mode after 15 minutes. 30 • Chapter 5: Setup Mode AC-7400 Gas Monitor Operator’s Manual...

  • Page 31: Chapter 6: Advanced Configuration Menu

    To leave the settings as they are, press MENU (Next). Factory settings are: • Channels 1-8 (or 12) “On” • Relays set at “10, 15, 20 and 25” • All relays set to “Auto Reset” / “Increasing” AC-7400 Gas Monitor Operator’s Manual Chapter 6: Advanced Configuration Menu • 31...

  • Page 32: Fault Relay Setup

    3. Failsafe: Press ADD or SUB (Yes/No—as indicated on the display screen) to setup Relay 1 as failsafe (or not failsafe). To leave the setting as it is, press MENU (Next). 4. Repeat Step 1 through Step 4 for Relays 2, 3, and 4. 32 • Chapter 6: Advanced Configuration Menu AC-7400 Gas Monitor Operator’s Manual...

  • Page 33: Modbus Setup

    Exiting the Advanced Configuration Menu 1. Press ESC at any time to exit the Advanced Configuration Menu. 2. Close the enclosure box. 3. Clamp down the enclosure latches. AC-7400 Gas Monitor Operator’s Manual Chapter 6: Advanced Configuration Menu • 33...

  • Page 34: Chapter 7: Maintenance

    2. To enter Relay Test Mode, from Normal Operating Mode, press and hold RESET/ESC. 3. Starting with Relay 1, the relays will activate in 5-second intervals. 4. To return to Normal Operating Mode, release and press RESET/ESC. 34 • Chapter 7: Maintenance AC-7400 Gas Monitor Operator’s Manual...

  • Page 35: Troubleshooting

    Table 2 describes symptoms, probable causes, and recommended actions for the most common problems you may encounter with the AC-7400. NOTE: This troubleshooting guide describes AC-7400 problems only. See the detector head operator’s manuals for preventive maintenance procedures that apply to the detector heads installed on your AC-7400.

  • Page 36: Chapter 8: Parts List

    Chapter 8: Parts List Table 3 lists the part numbers and descriptions for replacement parts and accessories offered for the AC-7400 Gas Monitor. Table 3: Parts List, AC-7400 Gas Monitor Part No. Description 18-0107RK Conduit hub (3/4 in.) 51-0040-RED Strobe/horn, 20 - 28 VDC, Cl. I Div. 1 Zone 1 71-0551 AC-7400 Gas Monitor Operator’s Manual (this document)

  • Page 37: Appendix A: Relay Operation

    When using a Wet Contact Relay, power should run through the “COMM” terminal to the end equipment. Figure 17: “Dry” Contact Relay Configured as a “Wet” Contact AC-7400 Gas Monitor Operator’s Manual Appendix A: Relay Operation • 37...
  • Page 38 The NC (normally closed) relay contacts are open during non-alarm operation and close when the appropriate alarm condition occurs. Figure 18: Relay Circuit Schematic 38 • Appendix A: Relay Operation AC-7400 Gas Monitor Operator’s Manual...

  • Page 39: Appendix B: Rs-485 Modbus Output

    -, 2 ' '  '  3 1  .  1 !"#$ ,.  -, 2 ' '  '  3 1  . AC-7400 Gas Monitor Operator’s Manual Appendix B: RS-485 Modbus Output • 39...
  • Page 40  +*$# , 7 / ,  ' 66/  % # 4#66  +*$# , 7 / ,  ' 66/  % # 4#66  +*$# , 7 / ,  ' 66/  40 • Appendix B: RS-485 Modbus Output AC-7400 Gas Monitor Operator’s Manual...
  • Page 41  +*$# , - /,  ' 1/  %  8 4" 1  +*$# , - /,  ' 1/  %  8 4" 1  +*$# , - /,  ' 1/  AC-7400 Gas Monitor Operator’s Manual Appendix B: RS-485 Modbus Output • 41...
  • Page 42 ! 9 ,,,.5 1   '  '' %  2  45  !"#$ ! 9 ,,,.5 1   '  '' 42 • Appendix B: RS-485 Modbus Output AC-7400 Gas Monitor Operator’s Manual...
  • Page 43 %  " 0 4+  +*$# , - /,  0 /  ' 0 %  " 0 4+  +*$# , - /,  0 /  ' 0 AC-7400 Gas Monitor Operator’s Manual Appendix B: RS-485 Modbus Output • 43...
  • Page 44 ,     0 &    +  , 7  ,$     0 &   +  , 7  44 • Appendix B: RS-485 Modbus Output AC-7400 Gas Monitor Operator’s Manual...
  • Page 45  %+,6   + +  +7 0 2+ +!8 + +  &  +  *!   ();    '" <   &  (#: 1 ('5 %+=+ 2+ AC-7400 Gas Monitor Operator’s Manual Appendix B: RS-485 Modbus Output • 45...
  • Page 46  $$ *( & 5'! &  '!   5'  5* #<  '5 & '5    ,6 & #>  *@  77 * 4 46 • Appendix B: RS-485 Modbus Output AC-7400 Gas Monitor Operator’s Manual...

  • Page 47: Ac-7412 (12 Channel) Register Map

    (  " /  #* 0  "  + "  ,+' - .  #* #   " / #* (  " /  #* 0  " AC-7400 Gas Monitor Operator’s Manual Appendix B: RS-485 Modbus Output • 47...
  • Page 48  ,+' -  2  *   #  1   * (3  ,+' -  2  *   #  1 48 • Appendix B: RS-485 Modbus Output AC-7400 Gas Monitor Operator’s Manual...
  • Page 49 * 66/  ( ' 4'66  ,+'  7 /   * 66/  ( 8#$ 4& 1  ,+'  - /  * 1/  * #$ AC-7400 Gas Monitor Operator’s Manual Appendix B: RS-485 Modbus Output • 49...
  • Page 50 * 66/  (  ' 4'66  ,+'  7 /   * 66/  (  ' 4'66  ,+'  7 /   * 66/  50 • Appendix B: RS-485 Modbus Output AC-7400 Gas Monitor Operator’s Manual...
  • Page 51 (  & 0 4,  ,+'  - /  0 /  * 0 (  & 0 4,  ,+'  - /  0 /  * 0 AC-7400 Gas Monitor Operator’s Manual Appendix B: RS-485 Modbus Output • 51...
  • Page 52 1 # # $ # "*  ** (  2 # 45  %&' % 9 .5 1 # # $ # "*  ** 52 • Appendix B: RS-485 Modbus Output AC-7400 Gas Monitor Operator’s Manual...
  • Page 53  ,+'  - /  * 1/  * #$ (  2 # 45  %&' % 9 .5 1 # # $ # "*  ** AC-7400 Gas Monitor Operator’s Manual Appendix B: RS-485 Modbus Output • 53...
  • Page 54  +# 20   --.  #* #*   )  6  +# 20   --.  #* #*   )  6 54 • Appendix B: RS-485 Modbus Output AC-7400 Gas Monitor Operator’s Manual...
  • Page 55   ,3 # 8  * ,   7  %  ,3 # +#  * ,   7       !" #   $% AC-7400 Gas Monitor Operator’s Manual Appendix B: RS-485 Modbus Output • 55...
  • Page 56 4$ (); &  '  %% *(  5'" '"  5'  5* $<  '5 '5 $&  -6 $>  *@ 77 * 4 56 • Appendix B: RS-485 Modbus Output AC-7400 Gas Monitor Operator’s Manual...

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