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6
MN301535 Rev A
Safety Precautions
Step Three
Electrical Shock Hazard:
It is possible to contact components on the controller that carry high voltage,
causing serious injury or death. All power to the controller and the relay circuit(s) it controls should be
turned OFF prior to working on the controller. If it is necessary to make adjustments during powered
operation, use extreme caution and use only insulated tools. Making adjustments to powered controllers is
not recommended. Wiring should be performed by qualified personnel in accordance with all applicable
national, state and local electrical codes.
Install In a Dry Location:
The controller housing is not designed to be immersed. When installed
properly, it should be mounted in such a way that it does not normally come into contact with liquid. Refer
to an industry reference to ensure that compounds that may splash onto the controller housing will not
damage it. Such damage is not covered by the warranty.
Relay Contact Rating:
The relay is rated for a 10 amp resistive load. Many loads (such as a motor during
start-up or incandescent lights) are reactive and may have an inrush current characteristic that may be 10
to 20 times their steady-state load rating. The use of a contact protection circuit may be necessary for your
installation if the 10 amp rating does not provide an ample margin for such inrush currents.
Make a Fail-Safe System:
Design a fail-safe system that accommodates the possibility of relay or power
failure. If power is cut off to the controller, it will de-energize the relay. Make sure that the de-energized
state of the relay is the safe state in your process. For example, if controller power is lost, a pump filling a
tank will turn off if it is connected to the Normally Open side of the relay.
While the internal relay is reliable, over the course of time relay failure is possible in two modes: under a
heavy load the contacts may be “welded” or stuck into the energized position, or corrosion may build up on
a contact so that it will not complete the circuit when it should. In critical applications, redundant backup
systems and alarms must be used in addition to the primary system. Such backup systems should use
different sensor technologies where possible.
While this manual offers some examples and suggestions to help explain the operation of FLOWLINE
products, such examples are for information only and are not intended as a complete guide to installing any
specific system.