Vacuum Control Systems
Chell has used its experience in the vacuum industry to develop a system
to precisely maintain the vacuum required to hold a rolling road in place.
The system measures the pressure in each cell on the road and uses this
to control vacuum valves underneath the road via a PID closed loop control.
Using this system enables to user to set a desired pressure to keep the
road flat and then this pressure will always be maintained regardless of
what transients occur. By maintaining just enough vacuum to keep the road
in place, the heat built up in the belt and platten is kept at a minimum
which therefore increasing the life of the belt.
The control of the system can be either analogue which uses a series of
discrete PID controllers or digital which uses a high speed PC acquisition
card to read the transducers and control the valving. Each system uses compact
pneumatically operated vacuum valves to control the pressure in each cell.
These valves are connected to a series of plenum chambers that are in turn
connected to one or a number of pumps.
Rolling Road Vacuum Monitors
Chell has also produced series of rolling road vacuum monitors that displays
the vacuum of any one of up to 33 cells. Like the control system above,
it uses high accuracy transducers (0.1% full scale accuracy) that are then
centrally conditioned and displayed.
RVM2000
This unit displays the pressure of 30 cells on an single LED display. Channel
selection is made via push button or rotary switches
RVM2020
This unit acquires the pressure and temperature (via thermocouple) signal
from up to 33 cells. It is digitised at the road and transmitted to a PC
where the signals can be displayed. The display can be configured to show
all the pressure / temperatures or a plot of any channel against time.
