Pump Protection; Automatic Fill - FlowLine Switch-Pro LC10 Series Manual

Application Examples

PUMP PROTECTION:

The key here is to install a level switch just above the outlet
to the pump. As long as the switch is Wet, the pump can
operate. If the switch ever becomes Dry, the relay will open
preventing the pump from running. To prevent relay chatter,
add a small relay delay.
Note: In this application, the relay to the pump must be
closed while the level switch is Wet. To do this, connect the
relay through the NO side of the relay and set Invert to the
OFF position. If power is lost to the controller, the relay will
de-energize and keep the circuit open preventing the pump
from running.

AUTOMATIC FILL:

This system consists of a tank with a high level sensor, a low level
sensor, and a valve that is controlled by the controller. Part of a
proper fail-safe design for this particular system is that if power is lost
to the controller for any reason, the valve filling the tank must be
closed. Therefore, we connect the valve to the NO side of the relay.
When the relay is energized, the valve will open and fill the tank. In
this case, Invert should be ON. The relay indicator will correspond
directly to the open/close status of the valve.
Determining the settings of LATCH and INVERT: This is the way
the system must operate:

When both the high and low sensors are dry, the valve will
open (relay energized), starting to fill the tank.

When the low sensor gets wet, the valve will remain open
(relay energized).

When the high sensor gets wet, the valve will close (relay de-
energized.

When the high sensor becomes dry, the valve will remain
closed (relay de-energized).
Latch: In any two-sensor control system, LATCH must be ON.
Invert: Referring to the logic chart in Step Eight, we look for the setting that will de-energize the relay (start the
pump) when both inputs are wet (Amber LEDs). In this system, Invert should be ON.
Determining A or B input connections: When LATCH is ON, there is no effective difference between Input
A and B, since both sensors must have the same signal in order for status to change. When wiring any two-
input relay section, the only consideration for hooking a particular sensor to A or B is if LATCH will be OFF.
MN301510 Rev A1
Step Seven
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