SPDM CONTROL BOX
2 – COMPOSITION
NIDEC ASI S.P.A. – SPDM CONTROL BOX USER MANUAL
IMSPDCB2EN
27
For the connection of the encoder, a cable with
twisted singularly shielded pairs shall be used.
Typical value:
single cable section: AWG24 ( 0,22mm
2
)
capacity between the cables : 50 pF/ m
capacity between cable and shied: 90 p/F m
SAP code: ELP20470101
It is compulsory:
to use an encoder with galvanic insulation between its structure and its electronic
circuits.
to use an encoder with protection against polarity inversion of power supply and
against short circuit at output.
to assembly the encoder on the motor so that to have galvanic insulation between
the motor housing/shaft and encoder.
Connect the shields of the cable to the shield bar in the converter using connections of the shortest length as possible (“pigtails”).
The ground connection of the shield is optional. It can be required to reduce the emission of radio frequency noise emitted both from the drive
and from the encoder. The connection must be performed connecting directly the shield to metallic parts (for example to the body of the
encoder avoiding pigtails) and to the ground terminal of the converter.
The cable must not be interrupted. If it
is not be possible to avoid
interruptions, provide for the absolute
minimum length of the “pigtail” in the
connections
of
the
shield
in
correspondence of each interruption.
Preferably use a connection method with sturdily-built metallic terminals for the terminations of the cable shield. This can be obtained by
blocking the single shields, or by supplying an additional total shield to be blocked by means of the terminal. The external sheath of the cable
must be removed as necessary to allow the installation of the terminal. The shield must not be broken nor open in this point. The terminals
must be installed close to the converter or to the feedback device with ground connections performed on a proper plate or on a similar metallic
surface.
Note
:
1
In the multidrive applications, if an external power supply is used, we suggest to use a power supply for every encoder.
2
If the encoder cables are longer than 60m we suggest to use encoder supplied at 24V.
3
The failure to ground connect the shield to both ends, due to noise voltage, can cause the breakage of the line driver of the
encoder and/or of the drive receiver.
