8
Relay Action
The relays outputs normally function in the direct acting mode, which means the relays turn ON with an increase in
pressure.
SP1
and
SP2
may be configured to act as reverse acting relays (refer to the
CtrL
menu item). When set
for reverse acting,
SP1H
and
SP2H
set the relay turn OFF point, and
SP1L
and
SP2L
set the relay turn ON point.
The above graph demonstrates direct and reverse action on process (pressure) change.
Alternating (Lead/Lag) Operation
The EDA is designed to easily operate a pair of pumps in an alternating operation to minimize pump wear. The unit
has programmable on and off set points for pump one and two. If the lead/lag feature is turned off then the relays
remain attached to their corresponding set points,
SP1H
and
SP1L
control relay 1 (pump 1) and
SP2H
and
SP2L
control relay 2 (pump 2). There is no alternating function.
If lead/lag feature is turned on then the relays will alternate with set points
SP1H
and
SP1L
to
SP2H
and
SP2L
with
every cycle of set points. The Last relay turned off will be last relay turned on with the next cycle. On the first cycle
on increase of pressure, assuming direct acting, the
SP1
relay (pump 1) will come on and then on further increase
of pressure the
SP2
relay (pump 2) will come on. On the subsequent decrease of pressure the
SP2
relay (pump 2)
will come off and then the
SP1
relay (pump 1) will come off. When pressure increases on the next cycle the relay
used on the last cycle for
SP2
will now be used for
SP1
, so that
SP1
now controls pump 2 and
SP2
now controls
pump 1. Even if
SP2
is not used on the pressure cycle the relays still alternate on next cycle.
Remote Site Products - 1-888-532-2706 - www.remotesiteproducts.com
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