Dwyer Series SCD Instruction manual

Dwyer Series SCD: Advanced Carbon Monoxide Detection and Control for Stand-Alone Systems

The Dwyer Series SCD is an intuitive and versatile carbon monoxide detector designed for a wide range of applications, particularly in smaller garages and service stations. With its ability to accept input from Dwyer GSTA and CMT200 series transmitters, the SCD provides relay contacts for direct control of fans or dampers, eliminating the need for a BMS controller.

Key Features and Capabilities:

Stand-alone operation with GSTA/CMT200 transmitters for direct fan/damper control
User-adjustable set point and differentials for efficient ventilation management

PDF Download

Document

Stand Alone Carbon Monoxide Detectors

Application and Installation Note

Series GSTA

While many parking garage applications require a carbon monoxide transmitter with a current or voltage signal to feed a BMS controller, there are applications for smaller garages or service stations for the carbon monoxide sensor to provide relay contacts to control the fan or damper operation directly without the BMS

Controller. These systems are considered stand alone systems. The Dwyer GSTA series and CMT200 series transmitters can meet the need of the applications that just require a current or voltage output. For stand alone systems, these transmitters can be combined with a SCD series process controller.

The SCD series controller accepts the signal input from the carbon monoxide transmitter and allows the user to adjust the set point and differentials for the fan / damper operation (typically around 25 PPM). In addition to the set point, the user can also set a high gas concentration alarm (normally set around 100 PPM). For systems that need to communicate with a building management system or other online management system, the SCD series has Modbus ® RS-485 serial communications as a standard offering to give feedback of the current gas concentration, set points, and output status.

For additional energy savings, the SCD series controller has PID capabilities that can be used to drive a VFD to have better ventilation control. Both the transmitters and the SCD can be powered using a common 24 VDC power supply such as our model SCD-PS. For applications that require additional sensors, pluggable slave modules are available that allow the controller to be expanded to have multiple carbon monoxide sensor loops.

Programming Guide for the SCD Series

All programming will be configured either at the factory or using the communications port. For the communication port, programmer will need a model

MN-1 RS-485 to USB converter, laptop, and SCD-SW configuration software.

Series SCD

SERIES SCD PARAMETER SETTINGS

INITIAL SETTING PARAMETERS

Input: 4 to 20 mA.

Units: None.

Scale High: 200.

Scale Low: 0.

Control Mode: On-Off (PID if using with VFD).

Heat/Cool Selection: Cool.

Alarm 1 Type: 11-high alarm with hysteresis.

Communication Data: Set to match BMS settings.

OPERATING SETTING PARAMETERS

Set Point: 25 (or different PPM value depending on local requirements)

Alarm 1 Set Point: 100 (or different PPM value depending on local requirements)

REGULATION SETTING PARAMETERS

Cooling Hysteresis (Differential): 5 (or different PPM setting depending on local code)

Process Input Offset: Only if there is any adjustment required due to sensor drift or error due wire resistance.

Modbus ® is a registered trademark of Schneider Automation, Inc.

DWYER INSTRUMENTS, INC.

Phone: 219/879-8000

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A. Fax: 219/872-9057 www.dwyer-inst.com

e-mail: [email protected]

Sample Wiring Diagram for 3 Carbon Monoxide Loops

SCD-PS

POWER SUPPLY

SCD-1033

BOTTOM

VIEW OF

SCD-1033

SCD-2033 SCD-2033

TO STROBE

LIGHT/BUZZER

FAN/DAMPER

MOTOR CONTROL

TO BMS

CONTROLLER

RS-485 MODBUS

GSTA GSTA GSTA

DWYER INSTRUMENTS, INC.

Phone: 219/879-8000

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A. Fax: 219/872-9057 www.dwyer-inst.com

e-mail: [email protected]

Hello! I am an AI chatbot specifically trained to assist you with the Dwyer Series SCD Instruction manual. I have thoroughly reviewed the document and can help you locate the exact information you need or explain the content in clear and simple terms. Whether you’re looking for guidance on specific features, troubleshooting steps, or general usage, feel free to ask your questions. The more details you provide about your concerns or needs, the more accurately and effectively I can assist you!