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Siemens Building Technologies Application :68 RWD68/68 - 02.2001

HVAC Products RWD68 1

RWD68/68

RWD68 Universal Controller

Application 68

Maximum priority

Room temperature control

Chilled water control valve

Chilled water pump output

Control (P or PI)

Room temperature control

Proportional control ( 0..10Vdc ) of the chilled water valve.

Digital output to energise chilled water pump ( dependent )

Maximum priority function to control the cooling valve.

Optional day / night set point adjustment .

........RWD68.......

RWD68/68

Room temperature sensor

Input from other controllers

Time clock or switch

2-port chilled water valve

Chilled water pump

Personal computer

Universal analogue input - main sensor

Auxiliary analogue input

Digital input

Analogue output

Digital output

Communication port

0..10Vdc cooling outputs

other controllers

• Room temperature sensor can be selected as Ni1000, Pt1000, or active sensor.

• Adjustable differential of digital output Q1.

• Adjustable proportional band of analogue output Y1.

• Integral action function selection and adjustment for output Y1.

• 24Vac controller supply voltage

• 0..10Vdc modulating control valve

• The cooling coil control valve is controlled by the highest call for cooling from other

zones via the final temperature controller and the maximum priority function in this

temperature controller.

• Day / night set points can be selected via time clock or switch.

• Dependent mode for the two cooling outputs, meaning that the digital output on and

off settings are set within the analogue output proportional band.

Supplemental features

Control

Operating modes

Summary of content (3 pages)

PAGE 1
RWD68/68 RWD68 Universal Controller Application 68 Maximum priority Room temperature control Chilled water control valve Chilled water pump output Control (P or PI) Room temperature control Proportional control ( 0..10Vdc ) of the chilled water valve. Digital output to energise chilled water pump ( dependent ) Maximum priority function to control the cooling valve. X1 X2 S1 Y1 Q1 PC RWD68/68 Optional day / night set point adjustment .
PAGE 2
Description of operation The temperature sensor senses the room conditions and on a rise in temperature the RWD68 via Y1 analogue output is compared to other zone controllers . The maximum call for cooling from other zone controllers is fed to the X2 input of the final temperature controller and via the maximum priority function of Y1 the highest call for cooling controls the position of the cooling valve.
PAGE 3
Main Display The main display shows , a) Whether Q1 is On or Off ( = off, = on ) b) Y1 output in Volts dc. (0..10V = 0..100% range) c) Whether day or night set point is selected. (¤ = day, d) X1 value ( room temperature) in ° C. = night) Other displays are available by pressing the + button, and the various displays are listed below in sequence from the main display.