Operating Instructions

Chapter 2 – Applications
Basic Operation
10
Siemens Industry, Inc.
Owner's Manual
125-5111
2015-06-30
Chapter 2 – Applications
Basic Operation
The PRC-OAVS with Pressurization Control by Differential Flow Reset, Slow Actuation,
Floating or Analog Output and Heating by BTU Compensation provides Direct Digital
Control (DDC) technology for pressure independent Variable Air Volume (VAV) and
Constant Volume (CV) laboratory room applications.
Application 2931 PRC-OAVS with Pressurization
Control
The controller controls pressurization, ventilation, and room temperature in a laboratory
room served by one single-duct supply terminal with a reheat coil, and one general
exhaust terminal. The room differential pressure is maintained by a PID loop that
varies the difference between the supply and exhaust airflows. Once the proper airflow
difference is determined, airflow is then controlled by other PID loops that maintain the
selected difference between supply and exhaust airflows.
This version of the PRC uses low speed supply and exhaust actuation rather than high
speed actuation. Therefore, it should be used only where rapid room response to
pressurization changes are not required.
This application allows the user to individually select floating or analog actuation for the
supply, exhaust, and reheat actuators.
Application 2931 Control Diagram.
Application 2997 Slave Mode
Application 2997 is the slave mode application for the Pressurization Room Controller
(see Ordering Notes for product numbers). Slave mode is the default application that
comes up when power is first applied to the controller. Slave mode provides no control.
Its purpose is to allow the operator to perform equipment checkout before a control
application is put into effect and to set some basic controller parameters (CTLR
ADDRESS, APPLICATION, etc.).