Trane IntelliPak SAHL Series Installation, Operation And Maintenance Manual page 75

To arrive at the correct MCA, MOP , and RDE values for these units, you must perform two sets of
calculations. First calculate the MCA, MOP , and RDE values as if the unit was operating in the
cooling mode (use the equations given in Calculation #1 above). Then calculate the MCA, MOP , and
RDE values as if the unit was operating in the heating mode as follows. (Keep in mind when
determining LOADS that the compressors do not operate while the unit is in the heating mode).
For units using heaters less than 50 Kw: MCA = 1.25 x (LOAD 1 + LOAD 2 + LOAD 4) + (1.25 x LOAD 3)
For units using heaters equal to or greater than 50 Kw: MCA = 1.25 x (LOAD 1 + LOAD 2 + LOAD
4) + LOAD 3
The nameplate MCA value will be the larger of the cooling mode MCA value or the heating mode
MCA value calculated above.
MOP = (2.25 x LOAD 1) + LOAD 2 + LOAD 3 + LOAD 4
The selected MOP value will be the larger of the cooling mode MOP value or the heating mode MOP
value calculated above.
Select a fuse rating equal to the MOP value. If the MOP value does not equal a standard fuse size
as listed in NEC 240 - 6, select the next lower standard fuse rating.
Note: If selected MOP is less than the MCA, then select the lowest standard maximum fuse size
RDE = (1.5 x LOAD 1) + LOAD 2 + LOAD 3 + LOAD 4
The selected RDE value will be the larger of the cooling mode RDE value or the heating mode RDE
value calculated above.
Select a fuse rating equal to the RDE value. If the RDE value does not equal a standard fuse size as
listed in NEC 240 - 6, select the next higher standard fuse rating.
Note: If the selected RDE is greater than the selected MOP value, then select the RDE value to equal
These units will have two circuit values shown on the nameplate. The first circuit value will be the
refrigeration (cooling mode) values calculated using calculation #1 above. The second set of circuit
values shown on the nameplate will be for the electric heating circuit as follows.
MCA = (1.25 x LOAD 3)
Select a fuse rating for the electric heating circuit that's equal to the MOP value obtained in the
equation above. If the MOP value does not equal a standard fuse size as listed in NEC 240 - 6, select
the next lower standard fuse rating (see note below for exception).
Note: If selected MOP is less than the MCA obtained in the equation above, then select the lowest
RDE = LOAD 3
Select a fuse rating for the electric heating circuit that's equal to the RDE value. If the RDE value does
not equal a standard fuse size as listed in NEC 240 - 6, select the next higher standard fuse rating.
Note: If the selected RDE is greater than the selected MOP value, then select the RDE value to equal
Disconnect Switch Sizing (DSS)
•
DSS = 1.15 X (LOAD 1 + LOAD 2 + LOAD 4)
•
DSS = 1.15 X (LOAD 3 + Supply Fan FLA + Exhaust Fan FLA)
RT-SVX36G-EN
which is equal to or larger than the MCA, provided the selected fuse size does not exceed
800 amps.
the MOP value.
b. Dual Source Power units (200V and 230V)
standard maximum fuse size which is equal to or larger than the MCA, provided the selected
fuse size does not exceed 800 amps.
the MOP value.
Calculation #1 - SX, SF , SA, SL, or SS Single Power Source Units
Calculation #2 - All SEH_ Single Power Source Units
MOP = (1.25 x LOAD 3)
Installation
75