7 Replacing the DST Assembly
4. Plug the ribbon cable connector into the assembly and ensure that the lock has snapped into
place.
5. Tighten the screwed DC power connections using the bolts from the scope of delivery (TX25,
torque: 6.0 Nm (53.1 in-lb)). Ensure the correct position when doing so (BU = blue, BK =
black).
6. Ensure that all connections for the replaced assembly have been made correctly.
7. Position the enclosure lid on the DC-Connection Unit and first tighten the upper-left and lower-
right screws, and then the remaining screws crosswise (TX25, torque: 6 Nm (53 in-lb)).
8. Commission the inverter (see Section 8, page 25).
7
Replacing the DST Assembly
7.1
Checking the New Assembly
To ensure that the replacement of the assembly can be performed, the status of the new assembly is
to be checked prior to removal of the defective assembly.
Procedure:
1. Carefully remove the assembly upwards out of the packaging. When doing so, ensure that the
thermal grease is not damaged or contaminated.
2. Check the pattern of thermal grease on the rear of the assembly for damage and impurities.
3. If the pattern of thermal grease on the rear side of
the assembly shows evidence of damage, the
assembly must be replaced. If small impurities (see
image) are present, these can be carefully removed
using a pointed tool. The pattern must not be
destroyed when doing so.
4. Lay the assembly in the packaging until use.
7.2
Removing the DST Assembly
Requirements:
☐ The pattern of thermal grease must be undamaged and free from impurities (see Section 7.1,
page 18).
Procedure:
1. Disconnect the inverter from all voltage sources (see Section 5, page 12).
2. Remove the DC EMV assembly (see Section 6.1, page 14).
18
STP50-DC-EMV-DST-RM-xx-10
SMA Solar Technology AG
Replacement Manual