Outback Power Systems MX60 Installation And User Manual page 4

Mounting the MX60
Up to three MX60's can also be mounted on top of a PSDC. Below is a view from the top of the PSDC enclosure. The
MX60 will mount using 1" TSC threaded nipples to the 2" spacings. One knockout is provided and one pilot hole for the
second hole. The 1.83" spacings are for two Solar Boost controllers.
Figure 2 MX60 mounting options on the top of an OutBack PSDC, DC Disconnect Enclosure
Two 1" TSC threaded nipples may be used to secure the controller to the PSDC top for many installations. All of the
wires will fit through one knockout so the second can be used as a means of attachment. If two nipples are used for
wiring, then drill and through bolt to the PSDC top using a couple #10 (5mm) screws, lockwashers and nuts. Plastic
snap in bushings may be substituted for metal nipples if the two boxes are screwed together. The use of a 7/8 inch
spacer behind the MX60 when installed in either of the two rear positions will allow the mounting foot holes to be used to
secure the chassis back to the wall.
When mounting the MX in a confined space, be careful not to block the fan opening or the air inlet holes towards the
bottom of the chassis on either side. One side may be blocked, but not both. Although this will not damage the controller,
it will decrease efficiency and may cause it to shut off due to an overtemperature error..
Wire and Disconnect Sizing
When wiring the MX60 note that there is a current limit on the output at 60 amps and that the unit is listed to operate
continuously at 60 amps. There is no 80% derating as required by the NEC for fuses, conductors, and most circuit
breakers.
The MX60 is a buck type converter and does not boost the output current when the PV array peak power point voltage
is below the battery voltage as may happen on hot days in 24VDC PV and a 24VDC battery system or a 48VDC PV and
a 48VDC battery system.
This unit can supply up to 60 amps output depending on the nominal PV array voltage and the nominal battery voltage.
The output is current limited to 60 amps. To meet minimum NEC requirements, the output conductor should have an
ampacity after any temperature and conduit fill corrections of 1.25 x 60=75 amps (NEC 310.15, 690.8,9). This would
normally indicate that the output conductors would be 4 AWG, but a larger size may be required if there are temperature
and/or conduit fill corrections required. With an output conductor rated at 75 amps (1.25 time continuous output current),
a circuit breaker ratted for continous 100% duty at 60 amps (continuous output) like the Outback OBDC-60 breaker may
be used to provide the code-required output circuit overcurrent protection and disconnect.
The PV array output connected to the MX60 input may be as high 60 amps, but at this current level, there is no current
boosting or maximum power-point tracking due to the 60-amp output current limit. Additionally, the input current may
exceed 60 amps on bright sunny days and any excess power would be lost. The size and ampacity of the input conduc-
tors must be selected to handle 1.56 times the short-circuit current of the PV array. Any disconnect or circuit breaker
connected to the input conductors must also be rated at 1.56 times the short-circuit current for the PV array unless it the
breaker rated for 100% duty in its enclosure. If that is the case, the circuit breaker may be rated at 1.25 times the PV
array short-circuit current.
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