13
installation
(50 mA or less) a 2K-ohm 10 watt power resistor is recommended.
D.C. Loads with Triacs—Although most applications use AC input power
and AC on the triac outputs (alarm and shutdown), these triacs may be used
in DC applications providing minimum loading requirements are met. When
DC is used, a triac will automatically latch in the “on” condition after trip, thus
only “close on alarm” (N.O.) can be used. To reset an external reset switch,
the rest switch must be wired in series with the load.
To avoid large voltage drops during DC operation, the triac should be con-
nected as follows:
Shutdown:
Term 4 POS
Alarm:
Term 14 POS
Term 3 NEG
Term 13 NEG
120 mA Analog Switch Option—The special requirements of the above two
sections (Light Loads and D.C. Loads with Triacs) do not apply. However,
maximum current is limited to 170 mA
Control Settings
Setting Trip Points
The Model 440DR provides two trips: one for alarm and one for shutdown. The
first trip (alarm) is set at a vibration alarm level to provide early warning that the
condition of the machine is deteriorating. If the machine condition continues to
deteriorate, the shutdown trip provides protection against catastrophic failure.
The shutdown and alarm is set directly in inches/seconds or mm/sec.
Setting of Time Delay
An important feature of PMC/BETA switches is the built-in time delay. This
prevents triggering of the alarm or shutdown functions from transient increases
in vibration levels. It also avoids shutdown due to transitory vibrations occur-
ring during start-up.
The time delay is adjustable. It will have been set at the factory for three (3)
seconds unless your order specified otherwise.
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