Honeywell W7761A - Manual (Page 16)

EXCEL 10 W7761A INPUT/OUTPUT DEVICE
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average many space temperature sensors that are located in a zone that is controlled by the W7750 Constant Volume AHU
Controller.
Mixed-Output-Type Control
The W7761A Device can control mixed-output-types of applications such as PWM and staged control occurring simultaneously
with Series 60 Floating Control.
Occupancy Sensor
Excel 10 W7761A device can be connected to an occupancy sensor through a digital input. This is a device, such as a passive
infrared motion detector, that contains a dry contact (see following NOTE) closure to indicate whether or not people are present
in the space. The Excel 10 W7761A Device expects a contact closure to indicate the space is Occupied. See Fig. 18 in
Application Step 4, Prepare Wiring Diagrams, for details on wiring connections. This occupancy sensor can then be bound to
other Excel 10 controllers on the E-Bus or Excel 5000 controllers on the C-Bus through the Excel 10 Zone Manager. This
would allow the other Excel 10 controllers to use their physical inputs for monitoring other elements such as return humidity,
IAQ, etc. to achieve better control.
NOTE: The Excel 10 Controllers (W7750 CVAHU and W7761A RIO) have limited power available (only 9 mA at 4.8 volts) for
checking the digital inputs for contact closures. It is very important that the device used contains high quality,
noncorroding contacts with resistivity that does not degrade; that is, increase over time. Use noble metal (such as
gold or silver), pimpled or sealed contacts to assure consistent, long-term operation.
The recommended devices for use with the Excel 10 W7750 Controller and W7761A Device are the EL7628A1007 Ceiling
Mounted Infrared or the EL7680A1008 Wall Mounted Wide View Infrared Occupancy Sensors. If ultrasonic sensors are
required, the EL7611A1003 and the EL7612A1001 Occupancy Sensors are recommended. An EL76XX Power Supply/Control
Unit is required for use with these occupancy sensors. The EL7630A1003 can power up to four sensors, and is multi-tapped for
several line voltages. The EL7621A1002 can power three sensors and it connects to 120 Vac line voltage. The EL7621A1010
can also power three sensors but it connects to 277 Vac line voltage.
Window Open/Closed Digital Input
Excel 10 W7761A device can be connected to a window sensor to indicate whether a window in the space was opened. The
Excel 10 W7761A device can be connected to a dry contact (see the NOTE for the Occupancy Sensor and Fig. 18 in
Application Step 4. Prepare Wiring Diagrams, for details) or a set of contacts wired in series (for monitoring multiple windows)
to verify that the window(s) are closed. This window(s) sensor can then be bound to other Excel 10 controllers on the E-Bus or
Excel 5000 controllers on the C-Bus through the Excel 10 Zone Manager. The algorithm in the other Excel 10 controllers
expects a contact closure to indicate the window is closed. If an open window is detected, the algorithm in the other Excel 10
controllers changes the mode of operation to FREEZE_PROTECT, which shuts down the control functions, and watches for
low space temperature conditions. The freeze protection setpoint is 46.4
°
F (8
°
C), and the frost alarm occurs at 42.8
°
F (6
°
C).
Wall Module Options
As previously discussed, there are five basic varieties of the T7770. There is one variety of the PT3000 sensor and the T7780
DDWM (see the Product Names and the Construction sections). The T7770A,B,C,D 20Kohm NTC sensor—(current feature
that can be used with the RIO Device) and one PT3000 sensor can be configured on any of the four resistive inputs. The
T7780 is an E-Bus node and would not be directly connected to the RIO Device.
Dirty Filter Monitor
The air filter in the air handler can be monitored by the W7761A RIO device and an alarm issued by the Zone Manager when
the filter media needs replacement. The two methods of monitoring the filter are:
1. Connecting a differential pressure switch to a digital input on the W7761A.
2. Wiring a 2-to-10V differential pressure sensor to a voltage input on the W7761A. If the analog input sensor is used, its
measured value 0 to 5 inw (0 to 1.25 kPa) is compared to a user-selectable setpoint. The comparison is done in the
Zone Manager —valid range: 0 to 5 inw (0 to 1.25 kPa), and the Dirty Filter alarm is issued when the pressure drop
across the filter exceeds the setpoint.
Indoor Air Quality (IAQ)
The Excel 10 W7761A device can monitor IAQ using one of two different methods of detecting poor air quality. The first is with
an IAQ switch device connected to a digital input on the W7761A, where a contact closure indicates poor air quality, and an
alarm can be issued by the Zone Manager. The device can detect poor air quality using any desired measure such as CO
2
,
VOC, CO, etc. The second method, is through an analog input that connects to a CO
2
sensor (0 to 10V). The measured value
of CO
2
from this sensor (0 to 2000 ppm) is compared to a user-selectable setpoint (the comparison is done in the Zone
Manager —valid range: 0 to 2000 ppm), and an IAQ alarm can be issued when the CO
2
level exceeds the setpoint. The IAQ
sensor that is connected to the W7750 RIO, can be bound to other W7750 CVAHU Excel 10 controllers on the E-Bus.