The total cable resistance must not exceed 5K Ohms with the remote
switch closed. The total capacitance of the cable must not exceed 25nF
with the remote switch open. Wires to the remote switch should be run
separately from power carrying cables. Do not run the remote switch wires
in a conduit that also contains power cables. Capacitive coupling between
the adjacent cables may cause false triggering of the IPG20’s remote
input. For cable runs longer than 150 metres we suggest using 2 separate
wires to reduce capacitive coupling between the adjacent wires. When set
up this way cable resistance becomes the limiting factor for distance. The
following table sets out the resistance of typical copper wire of various
diametres.
Note that the cable resistance refers to the total resistance out to the
remote switch and back, as measured at the controller across the 2 remote
connection wires with the external remote switch closed. Where the
system is switching zones, the IPG20 can be triggered to repeat the
learning process to learn the pressure of the new zone.
If you select “use alarm relay” and then select “relay closed whenever
pump is stopped” (No. 2 Relay) that tells the controller you are going to
use valve sequencing. When you then get deeper into the menu and are
asked if you want to use cyclic running, if you enter “Yes” it asks you for
the running time, followed by the stopping time. After the stopping time a
new question pops up “learn the new pressure”. (It does not appear unless
you have previously selected to use the “alarm relay” and “closed when
pump is stopped”). That means it does not confuse users who don’t want
valve sequencing. By having such a question there it means a user can opt
for “No” and still use cyclic running along with an alarm relay that closes
whenever the pump is stopped. (In other words, NOT relearn the
pressure).
As an example, a water tank is located 2000 metres from the IPG20. Two
separate wires each 0.2mm^2 are run to the remote tank (total wire length
is 4000 metres). The resistance as measured across the 2 wires back at the
IPG20 (with the tank level switch closed) is 382 Ohms. This is well under
the 5,000 Ohm limit. The remote input to the IPG20 will operate properly
provide the wires are separated by sufficient distance that the capacitance
between them is less than 25nF. Capacitance should be measured
between the wires when the remote switch is open and it must be less
than 25nF.
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