Baseline Systems BaseStation 3200 - Manual (Page 48)

C h a p t e r 3 – A d v a n c e d P r o g r a m m i n g
Page 46
Baseline 3200
the zone is considered stable after the delay time. One minute after the delay time a valid flow is
calculated (over the last minute interval).
Design Flow
This is the flow rating for the mainline and is likely different from the design flow of the POC/flow
device. When a mainline has multiple POCs of different capacity, the controller will use the
constrained design flow to determine the actual available flow for watering. For example,
consider the following design flows: flow device #1 = 50 GPM, flow device #2 = 100 GPM, and
mainline #1 = 85 GPM. The controller would use 85 GPM for managing zone concurrency unless
flow device #2 was shut off (over budget) in which case it would use 50 GPM. With the Limit by
Flow box set to Y (yes) the controller will use the design flow of the individual zones (or learned
flow) and will turn on zones waiting to water until their design flow is equal or less than the
available flow on the mainline. For example, with 85 GPM available, three zones at 20 GPM and
a fourth at 15 GPM can be run at one time – later there may be two zones at 30 GPM and one at
20 GPM (it can’t always hit 85 exactly).
Variance Limit
This is the key to single zone shut down. The variance limit can be set from 0% (off) to 100%.
During normal program watering, the controller compares the sum of the design flow (or learned
flow) from all running zones against the measured flow of the flow device (or the sum of all flow
devices supplying water to the mainline). The measured flow may be higher or lower than the
expected flow. When the ratio becomes greater than the variance, then an alert is generated.
For example, if the expected flow is 50 GPM, and the flow variance is 10%, then the acceptable
flow range is 45 to 55 GPM (10% of 50 GPM is 5 GPM). The variance can either be high or low.
If the Zone Off is set to Y (yes), a high flow variance alert will trigger a zone isolation algorithm to
determine the zone (or set of zones) that is causing the high or low flow variance alert. Once al
alert is triggered, the currently running zones are marked as “suspects” and shut off. The
program continues to water with another set of zones and one of the suspect zones. If the
variance is within limits, the zone will be marked as good and watering will continue. If the
variance is out of limit, then the zone will be marked as a failure and shut down (two strikes and
you’re out). This isolation algorithm allows for watering to continue almost without interruption,
while isolating the faulty zone or zones.
Managing Zone Concurrency
There are two factors that determine zone concurrency. One of these has been cover in the
previous section and controls zone concurrency based on flow. The next factor is strictly set by
program and at a controller level. These limits are the ultimate constraint. If the controller is
going to water more than one zone at a time, it
must be configured to do so in the Zone
Concurrency menu under the Flow Menu dial
position. From the top level menu of the flow
menu dial position, highlight the Zone
Concurrency menu item and press ENTR – see
screen example to the right.
Zone concurrency is controlled at a total for the
controller, and then for each program. In this
example (with infinate water) if program A, B,
and C all started at the same time, only seven