TDE MACNO DSC-03N - Sizing of Protective Fuses and Cables; Auxiliary Power Supply (Optional)

User manual 6-2
DSC/DSCT Series
6.2.2. SIZING OF PROTECTIVE FUSES AND CABLES
The connection with the mains can be effectuated directly (DSCT) or with the insulating transformer (DSC).
Protective fuses must be provided to protect the cables and the drive in case of short-circuit; the cables must
be chosen reminding the size of the supplier and of the motor. With the direct insertion to the mains, it must
be provided a reactance in series to the supplier to limit the current peak and in part the disturbances on line.
For the peak current it’s enough a reactance with a drop of 1-1,5% of the voltage at the nominal current of
the supplier.
To choose the fuses follow these rules:
a) In case of direct connection (without a limiting current device) the peak of the start current must be taken
in count, and so the size of the fuse must be calculated from the data of the nominal current of the
autotransformer or of the transformer multiplied by a factor 2,5 or 3.
b) If there is a soft-start circuit, the multiplied factor can be just a little higher than one.
c) The section of the supplying cables must guarantee a correct intervention of the fuses.
ATTENTION
The necessity of the limiting device (SOFT START) can be evaluated estimating the output impedance of the
supplier, so without using that device, it must be higher than these limits:
SIZE 3 - 6 - 10 Z=> 0,21 OHM
SIZE 15 - 20 Z=> 0,16 OHM
SIZE 30 - 40 Z=> 0,12 OHM
SIZE 60 Z=> 0,08 OHM
SIZE OF THE INVERTER AUTOTRANSFORMER
(with Vcc≥1,7%Vn)
PASSING POWER
TRANSFORMER
(con Vcc≥2,5%Vn)
POWER
3 - 6 - 10 3,8KVA 5,8KVA
15 - 20 5,0KVA 7,5KVA
30-40 6,7KVA 10KVA
60 10KVA 15KVA
6.3. AUXILIARY POWER SUPPLY (OPTIONAL)
The power fault at the R,S,T input implicates the autonomy for a few seconds of the drive so that it results
impossible the manitenance of the data and of the encoder. To solve this problem the TDE MACNO drives
are provided of a second input for single-phase supply with an appropriate connector.
The auxiliary supply must be done with a single-phase TRANSFORMER having a power not higher
than 30VA (for a single inverter) and a second voltage of 220V/+10/-20% for the series DSC and
DSCT.
The connection must be executed as indicated in the paragraphs 3.1 and 3.2.
In the DSCT drives (3x380Vac) it’s necessary to give first the mains power and later the auxiliary supply,
otherwise the regulation does not switch on.