GE Multilin DFF Instruction Manual Download

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INSTALLATION AND MAINTENANCE

GEK-106166E

DFF Digital Feeder Relay

8. INSTALLATION AND MAINTENANCE

8.1 RECEPTION, OPERATION AND STORAGE.

DFF relays are supplied to the customer in a special package, which adequately protects it during transportation, as
long as this is performed in normal conditions. Immediately after receiving the relay, the customer should check
whether it shows any signs of transportation damage. If it is apparent that the relay has been damaged by
inappropriate handling, it must be immediately advised in writing to the carrier, and the damage must be reported to
the manufacturer.

For unpacking the relay, normal care should be taken in order not to lose the screws, documents and other auxiliary
elements also supplied in the carton box.

If the relay is not going to be installed immediately, it is recommended to store it in its original package, and keep it in
a dry, dust free and metal particles free place.

8.2 INSTALLATION

The place where the relay is to be installed must be clean, dry, free of dust and vibrations, and well illuminated to
facilitate inspection and tests.

The relay must be mounted on a vertical surface. Check the list of figures at the end of the manual for the drilling
diagram in order to do the panel cut out

As DFF design is based on state-of-the-art digital technology and the manufacturing is done under severe control
conditions with sophisticated high accuracy equipment, it is completely unnecessary to recalibrate the relay.

8.3 GROUND CONNECTION FOR SAFETY AND PERTURBATION REMOVAL.

A12 ground terminal (see figure 6) must be connected to ground in order to get a right operation of the perturbation
removal filters included in the system. For securing the maximum protection, this connection must be as short as
possible (preferably 25 cm or less). In this way, the capacitors internally connected between outputs and ground
deflect the high frequency perturbations directly to ground without crossing the electronic circuits, so that these
circuits are perfectly protected.

Besides, safety of the staff that handles the relay is guaranteed by means of this connection, as the whole chassis is
grounded.

8.4 MAINTENANCE

Due to the primary role that protection relays have in any installation, it is recommended that a periodic test program
is followed. The intervals between these tests vary depending on the application, as well as on the experience and
customs of the user. DFF provides self-diagnosis functions that allow to immediately detect failures of the circuitry
with the only help of the keyboard and the display. Although this self-diagnosis capability does not reduce the
average time between failures, it increases the availability of the protection thanks to the possibility of drastic
reduction of the failure detection.

The group of tests that can be done to verify the whole operability of DFF equipment is deeply described in

ACCEPTANCE TESTS

chapter

The majority of the protection and communication functions are integrated in two different EPROM based programs,
because of this the rate of failures is significantly lower to the ones of previous designs (electromechanical or static
analog relays). Besides this there is no need of relay recalibration after years of use.

Possible failures of the communication microprocessor do not affect to the protection functions, which are
implemented by means of a dedicated microprocessor.