5
For example, assume that the test
is enabled with a START TEST
time of 15 seconds. When a pump
is called a timer is started for that
pump. If the timer reaches 15
seconds and the AUX/DIS input
for that pump has not been shorted
to ground then a fail to start test
failure is set for that pump. The
pump is then disabled and the
next available pump is called in
its place. This failure condition
is displayed on the front panel
and will remain active until reset
by either a reset button or reset
input. The high level alarm will
also reset this condition. This
is to make sure that a broken or
misadjusted check valve switch
does not cause an overflow.
Pump Up
Operation
Pump up mode is used in
situations, like water distribution,
where the pumps must maintain
a pressure or fill a tank (like a
water tower). For the purposes of
this description assume we have
three pumps which will be used to
maintain the level in a water tank.
The level is sensed by a pressure
transmitter mounted in the base of
the tank and all three pumps send
water to the tank.
As water is dispensed from the
tank the level drops. If the level
drops far enough to reach the lead
on setpoint then the lead pump is
called to run. This should cause
the level to rise until the lead off
setpoint is reached and the pump
is shut down. If the alternator
is on then the lead pump will be
sequenced to the next available
pump. If the level continues to
fall then the lag on setpoint will
be reached and the lag pump will
be called. As in pump down
operation each pump has separate
on and off setpoints and there are
setpoints for high and low alarm.
Unlike pump down the pump up
mode does not have a float backup
system.
Pump
Alternation
The NOVUS 4000 has an automatic
alternation system which can be
used to cause a different pump to
be used each pump cycle. This
is useful to equalize pump wear.
When the alternator is off the lead
pump can be selected and that
pump will always be called first.
The alternator on the NOVUS
4000 is controlled by a toggle
switch on the front panel. When
the switch is in the up position
the alternator is on and the lead
pump will be changed each cycle.
When the switch handle is in the
center position the alternator is
off and the lead pump is selected
by pushing the handle down. The
handle has a spring return from
the down position. Each time the
handle is pushed down the lead
pump will be incremented to the
next available pump. The current
lead pump is displayed on the right
side of the first line of the display
(LP=2).
For systems with two pumps,
alternation, if on, simply swaps
lead pump duty between the two
pump each pump cycle. If there
are three pumps, alternation can be
either of two options. In normal
alternation of each pump cycle the
next available pump is selected
as lead so that if all pumps are
available then each will be lead
every third time. The other option
is jockey pump. In this type of
system pump 1 is a small pump
and pumps 2 and 3 are large. The
small pump (pump 1) is always
the lead pump and the other two
pumps alternate. When either of
the two large pumps is on the
small one is turned off. This is
useful in systems where demand
can be low at some times and large
at others.
Pump
Startup
When the NOVUS 4000 is first
powered up it executes an internal
self test. During this test many
internal functions are checked and
the displays are sequenced. The
system is controlled by an internal
microcomputer which is monitored
by a watchdog timer system which
will restart the system in the
unlikely event that the program
fails to execute properly. After
the self test is complete several
timers are started which prevent
any relay outputs from activating
until all of the system inputs have
had a chance to settle and all of the
input filtering has resolved to their
proper values.
Front Panel
Indicators & Controls
Figure 1 is a view of the front
panel of the NOVUS 4000. It
includes eight LED lamps, a 32
character LCD display, 5 push
buttons, one toggle switch and one
adjustment knob. They have the
following functions:
1. PUMP 1 THRU PUMP
3 LAMPS
These three green LED lamps
indicate which pump is
currently being called.
2. OFF LAMP
This green lamp indicates that
no pumps are currently called
to run.
