MN301520 Rev A1
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Appendix
Step Eight
LATCH - ON VS OFF:
The relay can either be an independent relay (high level, low level or pump protection) with Latch OFF or can
be a latching relay (automatic fill or empty) with Latch ON.
With Latch OFF, the relay will only
respond to INPUT A. INPUT B will
be ignored while Latch is OFF.
Invert OFF
Latch OFF
Input A*
Input B*
Relay
ON No
Effect ON
OFF No
Effect OFF
Invert ON
Latch OFF
Input A*
Input B*
Relay
ON No
Effect OFF
OFF No
Effect ON
With Latch ON, the relay will
actuate when INPUT A and INPUT
B are in the same condition. The
relay will not change its condition
until both inputs reverse their
state.
Invert OFF
Latch ON
Input A*
Input B*
Relay
ON ON ON
OFF ON
No
Change
ON OFF
No
Change
OFF OFF ON
Invert ON
Latch ON
Input A*
Input B*
Relay
ON ON OFF
OFF ON
No
Change
ON OFF
No
Change
OFF OFF ON
Note:
Some sensors (particularly buoyancy sensors) may have their own inverting capability (wired NO or
NC). This will change the logic of the invert switch. Check your system design.
CONTROLLER LOGIC:
Please use the following guide to understand the operation of the controllers.
1.
Power LED:
Make sure the Green power LED is ON when power is supplied to the controller.
2.
Input LED(s):
The input LED(s) on the controller will be Amber when the switch(es) is/are wet and Green
or OFF when the switch(es) is/are dry. If the LED's are not switching the input LED, test the level switch.
3.
Alarm Relay (1 input):
When the input LED turn OFF and ON, the relay LED will also switch. With invert
OFF, the relay LED will be ON when the input LED is ON and OFF when the input LED is OFF. With invert
ON, the relay LED will be OFF when the input LED is ON and ON when the input LED is OFF.
4.
Latching Relay (2 inputs):
When both inputs are wet (Amber LED's ON), the relay will be energized (Red
LED ON). After that, if one switch becomes dry, the relay will remain energized. Only when both switches
are dry (both amber LED's OFF) will the controller de-energize the relay. The relay will not energize again
until both switches are wet. See the Relay Latch Logic Chart below for further explanation.
TIME DELAY:
The time delay can be adjusted from 0.15 seconds to 60 seconds. The
delay applies to both the Make and Break side of the relay. The delay
can be used to prevent relay chatter, especially when you have a liquid
level that is turbulent. Typically, a slight rotation clockwise, from a
position of all the way counter-clockwise, is enough to prevent relay
chatter.
Note:
The delay has stops on each end of its 270° rotation.