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automatically reset the system and resume normal running as soon as pressure
passes the set or snap pressure point. This makes the E30 running in mode 3 an
ideal device for shutting down a pump if the pressure rises excessively but
resetting and letting the system resume normal operation as soon as the pressure
falls back to an acceptable level.
Mode 3 Remote Input
To set the E30 to operate in mode 3 rst select your preferred pressure units from
the menu and choose to either use or not to use the remote input function. If you
choose to use the remote input function the snap action pressure switch will only
operate while the contacts of the external switch are closed. The remote switch
can be any set of voltage free contacts such as the contacts of an external relay.
Mode 3 Relay Usage
In mode 3 you can choose to use either relay 1 or relay 2 as your preferred output
device. In the E30 relay 1 is the primary relay and it is intended to drive heavy
loads. Relay 1 can be used on its own as a set of voltage free contacts or it can
be used in conjunction with the HD solid state drive to directly control pump motors
up to 3.75kW single phase or via an interposing contactor that can be used to
switch pump motors of any size. Relay 1 has special features built in that allow
time for pump motors to wind up and wind down when starting and stopping.
The timers built into relay 1 limit the speed the relay can open and close to about
1.5 seconds per cycle. This is perfectly acceptable if the E30 is being used to
directly drive a pump motor. If relay 1 is chosen as the output device and the
intended application is frequency counting or some other fast response requirement
then the speed limitations of relay 1 will impede the high speed performance. For
such applications relay 2 should be used as its speed limit is only limited by the
speed at which its contacts can open and close.
To summarise, select relay 1 as the output device when controlling pump motors
directly with or without the HD drive implemented and choose relay 2 as the
output device for all other applications.
If you choose to use relay 1 then relay 2 will mirror relay 1’s action. It will be on
when relay 1 is off and it will be off when relay 1 is on. It can be used to control
an external alarm or simply in conjunction with relay 1 to provide a set of break
before make S.P.D.T. contacts. If you make relay 2 your chosen output device
then relay 1 will not be used. It will not respond to the state of relay 2, it will simply
remain open in all situations.
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