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Their functioning diminishes with age or following repeated responses as a result of
overvoltages. You can now check these varistors in the following way, paying attention to
the safety information in section 2 "Safety information" (page 6).
7. Remove the screws that secure the lid and remove the lid from the GTW1500 HF.
Disconnect the PE connection from the lid. Make sure that no voltage is present.
8. Using a continuity tester, check all the varistors to see if there is a conducting connection
between connectors 2 and 3. If there isn't, then that varistor is not working. The positions of
the varistors in the GTW1500 HF can be seen in the diagram in section 3.1 "Unit
description" (page 11).
9. Replace the varistor concerned with a new one as shown in the drawing to the right.
nsure the varistor is installed the right way round! If you do not receive a special tool for
operating the terminal clamps with your replacement varistors, please contact ProVista. As
an alternative, the terminal contacts can be
operated using a suitable screwdriver. Since the
failure of one varistor is generally due to factors
that affect all varistors in a similar way
(temperature, age, inductive overvoltages), it is
highly recommended that you replace both
varistors, not just the one that is obviously
defective. The varistors were specially
manufactured for use in the GTW1500 HF and
are not commercially available. They must be ordered directly from
ProVista
.
In case there are no spare varistors available the GTW1500 HF still can feed electricity
into the grid. The input is not protected against over-voltages in this case. Replacement
varistors should be obtained as soon as possible. In systems with a high risk of
over-voltages, the GTW1500 HF should not be operated with defective varistors
10. Reconnect the PE connection on the lid and close the GTW1500 HF .
11. Connect up the faultless PV generator strings to the inverter
12. Close off the unneeded DC input sockets using the protective caps supplied in the
accessories kit.
13. Switch the line circuit breaker to the "on" position
14. Now check whether the LED display on the GTW1500 HF indicates that the device is
functioning correctly.
15. Exchanging the AC FUSE
Exchanging the AC side fuses, if it breaks:
Turn off all the AC and DC switches and /or breakers, wait for at least 3 minutes, then
open the GTW1500HF, and exchange the fuse F3:
F3:
Littelfuse 314-15A
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