SMA SB 3300TL Installation - Manual (Page 34)

Exchanging Varistors SMA Technologie AG
Page 34 SB3300TL-11:SE2006 Installation Guide
5. If you have found a ground fault it is probably unnecessary to exchange the
varistors. Make sure to remove the ground fault instead. This should normally
be done by the installer of the PV plant. In this case proceed with point 10, but
without reconnecting the faulty string! Protect its PV plug connectors against
touching (e. g. by protective caps or insulation strip with sufficient electric
strength).
If you have not found any ground fault in the PV generators, probably one of
the thermally monitored varistors has lost its protective function. The varistors
are subject to wear and tear and their function is reduced in the course of their
aging or in case of repeated strain placed on them by surge voltages. You can
now check the varistors as described below while following the safety
instructions given in chapter 2 „Safety Instructions” (page 9).
6. Unscrew the lid of the Sunny Boy 3300TL and remove it. Disconnect the PE plug
inside the lid. Test safe isolation from supply.
7. Test all varistors for an electric connection between terminals 2 and 3. If there
is no electric connection the varistor is useless. The position of varistors in the
Sunny Boy 3300TL can be seen in chapter 3.1 „Device Description” (page 11).
8. Replace the defective varistor by a new one as
shown in the figure on the right. Ensure correct
orientation of the varistor! Please contact SMA
if you have not received special tools to move
the terminals (included in delivery of
replacement varistors). However, the terminal
contacts can also provisionally be released one
by one with a suitable screwdriver. The failure
of a varistor is normally due to circumstances
that apply to all varistors in a similar manner
(temperature, age, induced surge voltages).
We therefore strongly recommend not only to
exchange the defective one, but all two. These
varistors are specially manufactured for use in
the Sunny Boy 3300TL and are not
commercially available. They have to be
purchased directly from SMA Technologie AG
(SMA order name:“MSWR-TV-7“).
1
2
3
Unlock the
varistor with the
extractor tool
Remove varistor
The wire with
the little dent
must be inserted
into the terminal
number 1 when
you install the
new varistor