Honeywell W7750A Occupancy Sensor, Window Open/Closed Digital Input, Wall Module Options

EXCEL 10 W7750A,B,C CONSTANT VOLUME AHU CONTROLLER

available through Honeywell, or directly from the manufacturer, Mamac Systems (see Table 11 for ordering information).

Fig. 17 depicts a typical W7750 System with modulating heating valve using a pneumatic valve actuator. Also see Fig. 36 for wiring an MMC325 Pneumatic Transducer to a W7750A,B,C Controller and Fig. 37 for wiring a RP7517B Pneumatic Transducer to a W7750C Controller.

NOTE: When choosing the pneumatic pressure range, make sure that the close-off pressure is 2 to 3 psi greater than that of the spring range. When using a spring range of 5 to 10 psi with 10 psi as the closed posi- tion, do not use the 0 to 10 psi model of the MMC325 Transducer; use the 0 to 20 psi transducer as the recommended selection.

		HEAT
		COIL
MIXED	FAN	DISCHARGE
AIR		AIR
		+
FAN		PNEUMATIC
		ACTUATOR
STARTER		VALVE

1

T7560A,B OR T7770

	M
MMC325	PNEUMATIC
	TRANSDUCER

1PNEUMATIC MAIN OR BRANCH LINE MUST BE 1/4 IN. (6 MM) OR LARGER TUBING. A MINIMUM OF 6 FT (1.8M) OF TUBING

IS NEEDED IN A BRANCH LINE. M17495

Fig. 17. Modulating heat with pneumatic valve actuator.

MIXED-OUTPUT-TYPE CONTROL

The W7750B,C Controller provides control for mixed-output- types of applications such as PWM heating and staged cooling control occurring simultaneously with Series 60 Floating Economizer Damper Control.

Occupancy Sensor

Excel 10 W7750 Controllers provide a digital input for connection to an occupancy sensor. 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 W7750 Controller expects a contact closure to indicate the space is Occupied. See Fig. 27 through 35 in Application Step 4, Prepare Wiring Diagrams, for details on wiring connections.

The control algorithm in the Excel 10 Controller uses the occupancy sensor, if configured, to determine the Effective Occupancy (see Table 5) mode of operation. If the Time Of Day (TOD) schedule indicates an Occupied state, and the occupancy sensor contact is closed, the Effective Occupancy mode is Occupied. However, if the TOD schedule indicates an Occupied state and the occupancy sensor contact is open,

then the Effective Occupancy mode is STANDBY. The temperature control algorithm is then controlled to the STANDBY Cooling and Heating Setpoints.

If the occupancy sensor is not configured, a local controller can be put in the STANDBY mode only by either a one-to-one association of the occupancy sensor from another Excel 10 Controller to the local controller, or by receiving the STANDBY mode signal via the LONWORKS Bus.

NOTE: The Excel 10 Controller has 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), or pimpled or sealed contacts to assure consistent, long-term operation.

The recommended devices for use with the Excel 10 W7750 Controllers 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

A digital input is also provided for detecting whether a window in the space was opened. The Excel 10 W7750 Controller can be connected to a dry contact (see the following NOTE and Fig. 27 through 35 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. The algorithm expects a contact closure to indicate the window is closed. If an open window is detected, the algorithm changes the mode of operation to FREEZE_PROTECT, which shuts down the control functions, and watches for low space temperature conditions. The frost protection setpoint is 46.4° F (8° C), and the frost alarm occurs at 42.8° F (6° C).

NOTE: (This is the same NOTE as in the Occupancy Sensor section.) The Excel 10 has 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), or pimpled or sealed contacts to assure consistent, long-term operation.

Wall Module Options

As previously discussed, there are four basic varieties of the T7770 Wall Modules and two of the T7560 Digital Wall Module (see the Product Names and the Construction sections). Also, a T7770 and T7560 Wall Modules can be shared among two or more W7750s. The control algorithm must be given this wall module information when configuring the W7750 (see Excel E-Vision User’s Guide, form 74-2588).

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