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APPLICATION
R7426A,B,C Temperature Controllers use direct digital control
technology to provide more accurate and efficient operation of
heating, ventilation and air conditioning (HVAC) systems.
Parameters are preset for plug and play operation and provide
different control strategies for optimum system performance.
The controller performs proportional or proportional plus
integral (P+I) control and covers all space, supply air or water
flow applications within the specified ranges of 32°F to 122°F
(0°C to 50°C) or 32°F to 266°F (0°C to 130°C). Standard
Pt 1000 or NTC 20K ohm temperature sensors can be used.
The modern design with its easy to operate user interface and
LCD allows complete flexibility of control system design,
accurate parameter setting, and display of actual temperature
values, setpoints and outputs.
The R7426D Universal Input Controller covers all space or
discharge air humidity control applications and special
applications, such as pressure control, within 0 to 10 Vdc input
ranges. The controller provides input span adjustment to
match the transmitter output specification.
® U.S. Registered Trademark
Copyright © 2000 Honeywell Inc. • All Rights Reserved
Universal Input Controllers
TIME-INDEPENDENT CONTROLLERS
FEATURES
• Selectable proportional, proportional plus integral
(P+I), or (R7426D only) proportional plus integral plus
derivative (P+I+D) control.
• Pre-programmed control parameters.
• Digital parameter setting.
• Selectable direct/reverse acting output.
• 24 Vac power supply.
R7426A,B,C
• 3 inputs for temperature sensors.
• Automatic sensor type identification of Pt 1000 or
NTC 20K ohm.
• 3 digital inputs for plant/system On/Off, occupancy
(alternatively summer/winter changeover) and freeze
protection.
• Dehumidification control via humidity deviation input.
• Selectable floating output functions:
— Floating.
— 2, 3, 4, 6 or 15 stage On/Off (TRIAC).
— Pulse width modulation (PWM).
• Analog outputs 0/2 to 10Vdc selectable.
• Start-up routine.
• Space/supply limit or cascade control.
• Sequence control of heating, mixed air damper or
energy recovery system and cooling.
R7426D
• 2 analog inputs 0 to 10Vdc for transmitters.
• Control output monitoring and manual output signal
override.
• Master/submaster cascade control.
• Main variable control and optional high/low limit control.
• Input span adjustment.
• Temperature compensation input.
• Optional remote setpoint adjustment.
Application .......................................................................
Features ...........................................................................
Specifications ...................................................................
Ordering Information ........................................................
Installation ........................................................................
Operation .........................................................................
Operating Overview .........................................................
Appendix .......................................................................... 10
Control And Configuration Parameters ....................... 10
Parameter Details ....................................................... 12
R7426A,B,C,D
Temperature and
PRODUCT DATA
Contents
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1
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63- 2565
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Summary of Contents for Honeywell R7426A
- Page 1 Specifications ..............Ordering Information ............Installation ................ Operation ................. Operating Overview ............Appendix ................10 Control And Configuration Parameters ....... 10 Parameter Details ............12 ® U.S. Registered Trademark Copyright © 2000 Honeywell Inc. • All Rights Reserved 63- 2565...
- Page 2 Control ranges: Operation Mode: Freeze protection (normal). R7426A,B,C: 32 ° F to 122 ° F (0 ° C to 50 ° C) or 32 ° F to 266 ° F Potential Free Contact: open > 40kW, closed < 100W. (0 ° C to 130 ° C).
- Page 3 R7426A,B,C,D TEMPERATURE AND UNIVERSAL INPUT CONTROLLERS Approvals: 6 (152) 1-7/16 (37) Protection class II. NEMA 1, IP30 or (with front panel mounting only ) IP40. FCC Part 15, Class B. Accessories: 43193862-001 Front panel mounting frame. NTC 20K ohm sensors for CPATYP 3 (10 to 20K ohms): 4-1/8 –...
- Page 4 R7426A,B,C,D TEMPERATURE AND UNIVERSAL INPUT CONTROLLERS UNOCCUPIED COMPENSATION UNOCCUPIED COMPENSATION MAIN FREEZE MAIN FREEZE SENSOR TEMPERATURE SENSOR TEMPERATURE PROTECTION PROTECTION SENSOR SENSOR – – OCCUPIED OCCUPIED LIMIT OR LIMIT OR – – PLANT/ PLANT/ CASCADE CASCADE CPA/SPA CPA/SPA SYSTEM SYSTEM...
- Page 5 R7426A,B,C,D TEMPERATURE AND UNIVERSAL INPUT CONTROLLERS R7426 Temperature Control R7426B,C Control with Heating, Mixed Air Dampers and Cooling Depending on the deviation signal, the control output (O1) value is calculated and converted to a floating signal. Select direct or reverse action using the DIR/REV parameter (cooling Sequence Control is Dir, heating is Rev).
- Page 6 Greater than exhaust air MINPOS by setting the control parameter DIR/REVO1 to Cho . temperature NOTE: This is provided only on the R7426A controller. Less than exhaust air Included in direct acting A potential free contact can be used between terminals 1 and...
- Page 7 OMode is 0, OxMode (where x is 1 or 3) is 3. Table 5. Freeze Protection Actions. 2-STAGE ON/OFF SEQUENCE CONTROL The R7426A,B controllers convert the output signal into a Output Function Freeze Protection Action 2-stage On/Off sequence output signal suitable for operating Outputs (in percent) relays.
- Page 8 Main Setpoint CTRP1 Fig. 9) and the controller enters standard display mode (see Fig. 10). This mode displays selected input/output values. NOTE: Although the R7426A,B,C have four control modes CP.2 Limit/Cascade Setpoint CTRP2 (see Fig. 10), the R7426D controller has only Off and On.
- Page 9 R7426A,B,C,D TEMPERATURE AND UNIVERSAL INPUT CONTROLLERS Selecting Output Values TROUBLESHOOTING Output selection mode displays the output value and indicates manual overrides. An activated manual override is indicated Error Messages by a displayed F (fixed). Improper sensor inputs will trigger an error message to flash NOTE: Press the SET button to enter adjustment mode.
- Page 10 R7426A,B,C,D TEMPERATURE AND UNIVERSAL INPUT CONTROLLERS APPENDIX Control And Configuration Parameters NOTES: — For more details on parameters see the The controller includes two groups of settings (I and II) for Parameter Programming section. control and configuration parameters. These settings are —...
- Page 11 R7426A,B,C,D TEMPERATURE AND UNIVERSAL INPUT CONTROLLERS Table 10. Configuration Parameters. Parameter R7426 Name A B C D Description Default C.01 DIR/ x x Selects O1 output action to adapt valve or damper direction (Dir: DA, Rev: RA). REVO1 C.02 DIR/ Selects O3 output action to adapt valve or damper direction (Dir: DA, Rev: RA).
- Page 12 Startup parameter to On. final control devices. — The R7426A,B outputs are not configured. This is After power up reset (initial start) or the On/Off input signal done to avoid damaging installed devices by changes to On, the outdoor air and exhaust air damper (O1) sending improper output signals when power is will stay in the closed position (0 percent).
- Page 13 ) determines the reset effect signal (I02ext is 0) is available, or sensor I01 (I02ext is 1) is in either degrees (R7426A,B,C) or percent (R7426D). If I01 used for limit control. (I01) deviates by 50 percent of the throttling range (Xp1), this...
- Page 14 R7426B,C controllers. MINPOS determines the outdoor air damper actuator minimum position. It maintains the minimum With the R7426A,B,C, Xh is the maximum air temperature outdoor air damper setting even when temperature conditions increase (heating) or decrease (cooling) produced by the coil, call for a fully closed position.
- Page 15 Fig. 12. (%/S) IMPORTANT P= 100 Xw (%) Set the R7426A parameter Dir/RevO1 to Dir or Rev TIME to match the required heating or cooling application. If parameter Dir/RevO1 is set to Cho (summer/winter changeover), parameter SOFFS is ignored. P + I + D CONTROL...
- Page 16 R7426A,B,C,D TEMPERATURE AND UNIVERSAL INPUT CONTROLLERS Derivative Decay Time/Amplification: td/vd (P.27/P.28) NOTES: — XOFFS = -SOFFS for heating control if Dir/RevO1 P+I+D control adds the derivative function to P+I control to is Rev. enhance control behavior. The derivative function opposes —...