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dropout and restore values for over and under voltage, over
and under frequency, as well as the associated time delays.
Switch Exerciser
The MX350 controller has a built-in exerciser that
can be enabled and set up from the \Exerciser\Info
screen. This feature allows the user to test the system
periodically or to setup a schedule for operating the
system periodically in order to minimize utility costs.
From the \Exerciser\Info screen the operator can access
all required setup parameters for scheduling exercises. It
also indicates as to when the last exercise took place
and when the next exercise will be performed.
The \Home\Exerciser\Setup page displays the MX350
Exerciser parameters as shown in Figure S6-17. Exercise
duration of exercise and whether or not the switch is to
transfer the load. The mode of operation of the exerciser
function can be selected with a time base of 1 day, 1 week,
14 days, 28 days, or 365 days. With a time base of 365 days,
up to 24 events can be scheduled (0-60 min). With all other
time bases, the number of exercise events is limited to 7.
Figure S6-17: Exerciser values on Home\Exerciser\Setup Page
Zenith Automatic Transfer Switch
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For each exercising event, the operator enters a start time as
well as a time of duration. In addition, the operator can select
the type of exercise as 'Genstart and Transfer' or as 'Genstart
only'. When the 'Gen Start only' mode is selected, the controller
will start the engine, but does not actually transfer the load.
In this mode, the readiness for the engine generator set is
tested. It does not test the functionality of the Automatic
Transfer Switch itself. In the 'Gen Start and Transfer' mode,
the controller starts the engine and actually transfers the load
to the alternative source. This mode can be used to test the
integrity of the emergency power system. It can also be used
to setup a schedule for times of operation when the switch
load will run on an alternative power supply. This could be
done, e.g., to avoid demand charges from a utility company.
If the operator chooses to abort an ongoing test, there is a
'Test Cancel' button on the \Exerciser\Info screen. This screen
also contains a 'Test' button that will take the user directly to
the Test screen. The \Home\Exerciser\Test page displays the
the Test screen the user can perform the same operations as
performed by the exerciser. Whereas exercises are performed
automatically, a Test always has to be initiated by the user.
Figure S6-18: System test choices on Home\Exerciser\Test Page
There are three types of tests: Fast Test, Xfer Load, and
No Xfer. The screen also provides an END button to abort
any of the three test types. To test the functionality of the
switch the operator can use the Fast Test option. With this
kind of test, the engine generator will start and the load will
transfer without going through any time delays. In order to
simulate a load transfer as if an outage was occurring, the
operator can select the Xfer Load test. With this test type,
the engine will start up and the load will transfer according
the time delay of the W timer. When the test is ended (by
depressing the END button), the switch will go through the U
timer delay before actually transferring back to the utility.
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