Rickard PCD Manual

INTRODUCTION
The RICKARD PCD may be supplied complete with electronic pres-
sure controls which will enable the damper to maintain a constant
branch duct static pressure at all times. The pressure controller may
be mounted remote from the PCD in a separate control panel.
In the case of the damper-mounted controller, a 220/24Volt trans-
former and 2m PVC power lead with plugtop are included and the
controller is completely pre-wired in the factory. In the case of the
controller which is mounted remotely, the contractor must provide a
24V AC power supply and must also complete the wiring between
the controller and the damper actuator.
The static pressure sensor is supplied loose, to be fitted to the
branch duct in a suitable position by the contractor. The intercon-
necting cable between the controller and the sensor form part of the
supply and although the standard length supplied is 20m, additional
cable may be supplied if required.
INSTALLATION
The PCD may be manufactured to any size required, both in terms of
the width and the height of the unit. Although the standard depth is
150 mm, this too may be varied to suit any requirements but may
not be less than 150 mm.
When damper widths exceed 1000 mm, the aluminium blades are
split and a mullion is fitted down the centre of the casing. In this
case two actuators would be fitted, one for each section. As a rule
the area of blades on one actuator should never exceed 0.5 m². For
example, a damper of say 1400 × 1400 mm would consist of four
sections, each 700 × 700 mm and each having its own actuator.
The standard PCD would be manufactured with 35mm sheet metal
flanges complete with four fixing holes on each flange or pre-
manufactured flanges such as MEZ flanges are available as an op-
tional extra.
The PCD must always be installed with the actuator on the down-
stream side of the vanes. The PCD may be installed with the Lindrive
actuator on the top or bottom depending on the specific installation,
but not on the sides (the vanes must always be horizontal).
The Pressure Sensor is supplied loose and is easily fitted to the duct
on site. Drill a 10mm diameter hole in the duct to accept the sens-
ing probe and fix the sensor by means of two self tapping screws.
Ensure that the sensing probe protrudes into the air stream and is
not obstructed by internal duct lining or any other such obstruction.
In all cases the pressure sensor for a branch duct should be fitted on
the branch duct itself and not in the feeder duct to the individual
terminal nor in the terminal unit itself.
Generally it is recommended that the sensor be fitted at a point
which is half to two thirds of the distance from the damper to end of
the duct run so that the most representative pressure is sensed.
Avoid placing the sensor close to bends or other obstructions.
OPERATION
To adjust the duct static pressure, turn the pressure adjustment po-
tentiometer screw. Clockwise rotation of this screw causes the PCD
to open and increase the duct static pressure. The flashing green
LED indicating light on the controller indicates that the controller is
transmitting a signal to drive the damper open. This signal will
continue even after the damper has reached the mechanical limit
stops, unless the setpoint has been reached. Note that 20 turns of
the potentiometer cover the full range of adjustment.
Pressure Adjustment
Potentiometer Screw
The frequency with which the light flashes is an indication of how
close the damper is to the required setpoint. As the duct static pres-
sure approaches setpoint, the flashing slows down and will stop
flashing altogether when setpoint is reached. In the same way, the
red LED indicating light indicates that the controller is transmitting a
signal to close the damper. At setpoint both lights are off. An indi-
cating light which remains on continuously means that the duct pres-
sure is far from setpoint and that the actuator is driving continuously
to correct the pressure. The problem in this case may be that the
static pressure upstream of the damper is incorrectly set.
DAMPER MOUNTED CONTROLS
In this case the pressure controller is mounted in a panel which is
attached to the side of the damper.
A 20m length (standard) of sensor cable with DIN type connector
fitted to one end, is attached to the controller and must be plugged
into the pressure sensor once it has been fitted to the branch duct.