GE Industrial Solutions ZBTE Series - Manual (Page 13)

Zenith ZTE/ZBTE Series Operation & Maintenance Manual Page 11 91 R -1000
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 periodi-
cally 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 10. Exercise type
and schedule are user-defined here for starting time,
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. With all other
time bases, the number of exercise events is limited to 7.
Figure 10
Exerciser Values on Home\Exerciser\Setup Page
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 alter-
native 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 MX350
system test choices, as shown in Figure 11. From 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 11
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.
Controller power supply
(UTA – universal transformer assembly)
System line voltage is transformed to 170Vdc to power
the MX350 controller and 24Vdc ungrounded to power
relays via the universal transformer assembly (UTA).
The power supply is termed “universal” because the same
unit handles all line voltages from 120Vac through
600Vac via an internal six-position jumper array. Figure 12
shows the external connections points for the UTA. The
UTA also features a 120Vac uninterruptible power supply
input and 24Vdc input battery options. 120Vac and
24Vdc (ungrounded) must be supplied together from an
uninterrupted power source. In addition, test terminals
are included for transformer voltage monitoring (see
Figure 13 for connection point definitions and Figure 14
for the UTA schematic).