Omron SX-F Instruction Manual Download

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Cable connections

Section 3-2

Note

The Brake and DC-link Terminals are only fitted if the Brake Chopper Option is
built-in.

!Warning

The Brake Resistor must be connected between terminals DC+ and R.

!Warning

In order to work safely, the mains earth must be connected to PE and the
motor earth to

3-2-2

Motor cables

To comply with the EMC emission standards the variable speed drive is pro-
vided with a RFI mains filter. The motor cables must also be screened and
connected on both sides. In this way a so-called “Faraday cage” is created
around the VSD, motor cables and motor. The RFI currents are now fed back
to their source (the IGBTs) so the system stays within the emission levels.

Recommendations for selecting motor cables

•

Use screened cables according to specification in table 7. Use symmetri-
cal shielded cable; three phase conductors and a concentric or otherwise
symmetrically constructed PE conductor, and a shield.

•

PE conductor cross-sectional are shall for cable size



16mm

be equal to

the used phase conductors, for cable size above 16mm

but smaller or

equal to 35mm

the PE conductor cross-sectional area shall be at least

16mm

. For cables > 35mm

the PE conductor cross-sectional area

should be at least 50% of the used phase conductor.

•

When the PE conductor in the used cable type is not in accordance with
the above mentioned cross-sectional area requirements, a separate PE
conductor should be used to establish this.

•

When the conductivity of the cable PE conductor is <50% of the conductiv-
ity of the phase conductor, a separate PE conductor is required.

•

Use heat-resistant cables, +60



C or higher.

•

Dimension the cables and fuses in accordance with the nominal output
current of the motor. See table 48, page 282.

•

Keep the motor cable between VSD and motor as short as possible.

•

The screening must be connected with a large contact surface of prefera-
ble 360



and always at both ends, to the motor housing and the VSD hous-

ing. When painted mounting plates are used, do not be afraid to scrape
away the paint to obtain as large contact surface as possible at all mount-
ing points for items such as saddles and the bare cable screening. Relying
just on the connection made by the screw thread is not sufficient.

Note

It is important that the motor housing has the same earth potential as the
other parts of the machine.

•

The litz ground connection, see fig. 26, is only necessary if the mounting
plate is painted. All the variable speed drives have an unpainted back side
and are therefore suitable for mounting on an unpainted mounting plate.

Connect the motor cables according to U - U, V - V and W - W.

Note

The terminals DC-, DC+ and R are options.

Switches between the motor and the VSD

If the motor cables are to be interrupted by maintenance switches, output
coils, etc., it is necessary that the screening is continued by using metal hous-
ing, metal mounting plates, etc. as shown in the Fig. 25.