GREYSTONE CD2OS Series Outside Carbon Dioxide Transmitter
INTRODUCTION
The CO2 transmitter uses Infrared Technology to monitor CO2 levels and outputs
a linear 4-20 mA or 0-5/0-10 Vdc signal. Features include a back-lit LCD with
user menu for easy installation and optional control relay with user
selectable temperature sensor outputs.
BEFORE INSTALLATION
Read these instructions carefully before installing and commissioning the CO2
transmitter. Failure to follow these instructions may result in product
damage. Do not use in an explosive or hazardous environment, with combustible
or flammable gases, or as a safety or emergency stop device or in any other
application where failure of the product could result in personal injury. Take
electrostatic discharge precautions during installation and do not exceed the
device specifications. Use 22 AWG shielded wiring for all connections and do
not locate the device wires in the same conduit with wiring used to supply
inductive loads such as motors. Make all connections in accordance with
national and local codes.
MOUNTING
Select a suitable mounting spot on an exterior wall where the CO2 sensor is
best protected from direct exposure to sunlight, wind, etc. preferably on a
north facing wall. Do not mount the sensor near opening windows,
supply/exhaust air louvres or other known air disturbances. Avoid areas where
the sensor is exposed to vibrations or rapid temperature changes. It is
recommended that the enclosure be mounted so conduit or cable-gland
connections be made on the bottom of the enclosure. See Figure 1.
Remove the cover by using a standard or flat screwdriver to loosen the four
screws as shown in Figure 2. As the screws are captive type, complete removal
of the screw from the cover is not required.
On the bottom of the enclosure, remove conduit/cable gland entry knockout (s)
as required. See Figure 3. Install a conduit fitting or cable gland as shown
in Figure 4. It is recommended that weatherproof conduit or cable gland
fittings be used.
Mount the sensor directly on an exterior wall using the four integrated
mounting holes that are provided on the enclosure. See figure 5. Select the
best mounting technique based on the exterior wall material. The 4 mounting
holes will facilitate a #10 size screw (not supplied).
After the base is securely fastened to the exterior wall, connect conduit to
conduit connector or feed cable through the cable gland and tighten.
Make wire connections as per the “Wiring” illustrations on Page 2. Once wiring
and set up are complete and re-install cover and secure by tightening the four
screws using a flat screwdriver.
WIRING
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Deactivate the power supply until all connections are made to the device to prevent electrical shock or equipment damage. Use 16-22 AWG shielded wire for all connections (only ground the shield at the controller end) and do not locate the device wires in the same conduit with wiring used to supply inductive loads such as motors. Pull at least six inches of wire into the enclosure and complete the wiring connection according to the wiring diagram.
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NOTE: The H (Heated) & N (Unheated) series have different connection terminals as shown on the diagrams.
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Select the desired signal output type by sliding the Output switch into desired position as shown in Figure 6. The factory default is “VOLT” and set to 0-5 Vdc. It may be changed to 0-10 Vdc during program set up. The “mA” setting provides a 4-20mA output.
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This is a 3-wire sourcing device. Connect the plus dc or the ac voltage hot side to the PWR terminal. The supply common is connected to the COM terminal.
The device is reverse voltage protected and will not operate if connected
backwards. It has a halfwave power supply so the supply common is the same as
the signal common. Several devices may be connected to one power supply and
the output signals all share the same common. Use caution when grounding the
secondary of a transformer or when wiring multiple devices to ensure the
ground point is the same on all devices and the controller. See Figure 7.
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The CO₂ analog output is available on the CO2 terminal. (see Figure 7) and connects to the controller analog input. Check the controller Analog Input to determine the proper connection before applying power. Both current and voltage signals are referenced to the COM terminal. The current output operates in the active mode and does not require a loop power supply (the signal current is generated by the transmitter and must not be connected to a powered input or device damage will result).
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The relay output is on the N.O. RELAY terminals as shown in Figure 8. The relay output is completely isolated and has a Normally Open (NO) signal. This signal can be used to directly control an alarm or ventilation fan. See specifications for switch rating.
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The optional two-wire temperature sensor output is available with various RTDs and thermistors to suit all control applications and is available as a twisted pair connection. All connections should be made using either butt-splices or soldering. The use of wire nuts is not recommended. See Figure 9
START-UP
Verify the device is properly wired and connections are tight. Ensure the mA /
VOLT switch is set for the correct signal type. Apply power and the LCD will
indicate the software version number, the output signal type and then the
sensor will begin a one minute warm-up countdown. When the warm-up time
expires the device will enter normal mode.
OUTPUT SCALING
The CO₂ output signal is scaled such that 4-20 mA (or 0-5 / 0-10 Vdc) equals
0-2000 ppm by default. The signal span may be changed via the Setup Menu from
1000 to 10,000 ppm in 500 ppm increments.
OPERATION
The output signal is available on the CO2 terminal and is connected to the BAS
analog input which reads the signal and calculates the CO2 ppm value using
correct scaling for the range and signal type. The CO2 value is used to
control output ventilation devices or initiate alarms. The CO2 value is also
displayed locally on the LCD.
If the relay is installed it can control a small fan or alarm by setting the
trip value and hysteresis to appropriate values.
If a temperature sensor is installed, it will be wired to an analog input of
the BAS that is set for the specific resistance type. This could be a 10 KΩ
thermistor, a 1000 Ω RTD or other sensor values. The BAS reads the resistance
signal and converts it to a temperature value.
NOTE: The outside enclosure slows the sensor response time to approximately
30 minutes for a 90% step change of CO2 concentrations.
RELAY MODE
The optional relay can be used as an alarm signal to indicate that a setpoint
has been exceeded. For the basic CO2 product, the relay may be configured via
the Setup Menu as a high or low alarm and the setpoint value, hysteresis and
on-delay time may be set. The relay will activate and close the contacts if
the CO2 measurement goes above the setpoint (for a high alarm) or below the
setpoint (for a low alarm).
If required, this action can be delayed by a time period (relay delay time) to
prevent false alarms. After the relay is activated, the measurement must fall
below the setpoint – hysteresis value (for a high alarm) or go above the
setpoint + hysteresis value (for a low alarm) to deactivate the relay and open
the contacts. The high/low assignment, setpoint, delay time and hysteresis
values may all be programmed via the Setup Menu as required.
The device has several parameters that can be configured locally via the Setup
menu using the keypad and LCD. Any changes made are saved in non-volatile
memory and are restored in case of a power loss. The menu can be accessed at
any time after the start-up mode and if there is 5 minutes of inactivity the
menu will close and normal operation will continue.
To enter the menu, press and release the key. This will enter the Setup Menu
step 1, pressing the key a second time saves the setting and advances to step
2. Each press of the key saves the current setting and advances the menu item.
The and keys are used to make changes to program variables by scrolling
through the available options. The first column below shows what will be
displayed on the LCD, including the default value.
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