General; Description; Application - Honeywell RP920A-D Service Data

GENERAL

DESCRIPTION

The RP920 Modular Pneumatic Controller, in
conjunction with remote sensors, provides Proportional (P)
or Proportional Plus Integral (p + I) control of temperature,
humidity, pressure, or dewpoint in WAC systems.

APPLICATION

In the mixed air control application (Fig. l), the primary
sensor modulates the outdoor and return air dampers
In a dual-input control application (Fig. 2), the RP920B
or D provides reset capability. Often, control of a building
is more efficient if the setpoint of the controller is reset to a
different value as a function of some parameter other than
COMPENSATION
SENSOR (OUTDOOR AIR)
VALV
N.O.
Fig, 2. Typical Dual-Input Control System.
LIMIT
CONTROLLER
MIXED AIR CONTROL SYSTEM
Fig. 1 Typical Single-Input Controller Applications.
through the primary controller (RP920C) maintaining a
constant mixed air temperature. The limit controller
(RP920A) and limit sensor sets outdoor air intake to
minimum.
In the hot water converter control application (Fig. l), the
primary sensor modulates the steam valve on the converter
to maintain the hot water temperature. On CPA models the
hot water temperature can be adjusted remotely using a
gradual switch.
PRIMARY
STEAM
SUPPLY
the controlled variable, in this system, outdoor air
temperature. To use compensation, a reset schedule must be
set up (Fig. 3).
F U L L
F U L L
COMPENSATION
COMPENSATION SENSOR
WHERE:
LOWEST VALUE OF CONTROLLED VARIABLE.
HIGHEST VALUE OF CONTROLLED VARIABLE.
VALUE OF COMPENSATION VARIABLE WHEN
CONTROLLED VARIABLE IS AT ITS LOWEST VALUE.
VALUE OF COMPENSATION VARIABLE WHEN
CONTROLLED VARIABLE IS AT ITS
Fig. 3. Compensation Reset Schedule.
3
M
CPA
1
2 4
r
CPA
, MODELS ONLY
4 8 9
OR C
2 3 1
DA
PRIMARY
SENSOR
IN HWS
r - l LINE
TO CONVERTER
HOT WATER CONVERTER
CONTROL SYSTEM
COMPENSATION
START
VALUE.
2 1 3 6 5 - l
85-O 142
a