Connection To The Converter; Converter Operation On A Grounded Network - Siemens 1LA8 Series Operating Instructions Manual

Cable grip and sealing insert
Note
Tighten the strain relief clamp screws; so that the
required clamping effect is achieved without damaging
the cable insulation, a tightening torque of 5 Nm is
recommended (see Fig.).
Internal PE ground conductor connection
The PE ground conductor connection between the
grounding terminal in the box enclosure and the motor
enclosure is made by means of the mounting screws of
the terminal box. The standard terminal box cover
mounting screws are adequate as potential bonding
between the terminal box cover and terminal box
itself.
The equipotential bonding between the terminal box
cover and the box enclosure is provided by means of
the standard cover mounting screws. A special
external ground cable is only installed if, for example,
flat seals are mounted without additional support.
When performing any installation work you must
always take care to ensure that all equipotential
bonding measures remain effective.
Final checks
Please check that:
• The electrical connections in the terminal box have
been made in accordance with the specifications
above and tightened to the required tightening
torque.
• The air gaps between non-insulated parts are
maintained:
≥ 8 mm up to 500 V, ≥ 10 mm up to 660 V and ≥ 14
mm up to 1000 V.
Be aware of protruding wire ends when checking this.
• The connecting cables are laid in an open
arrangement, so that the cable insulation cannot
be damaged during operation.
• The motor is connected-up corresponding to the
specified direction of rotation.
• The inside of the terminal box is clean and free of
any cable pieces.
• All gaskets and seals are undamaged.
• Unused openings in the terminal boxes are properly
closed off.
Then close the terminal box and tighten the terminal
box cover screws to 22 Nm.

3.7 Connection to the converter

Temperature sensor
Whenever motors are labeled for operation with a
converter, they are usually equipped with an upgraded
set of temperature sensors. This is because of the
reduced effectiveness of the fan at lower speed ranges
and the low temperature limits.
3.8 Converter operation on a grounded
network
Parallel PE conductors
In the case of current-limited converters without
ground fault monitoring, PE conductor currents of up
to 1.7 times the external conductor current can arise
if there is a ground fault on the output side. Neither
the PE conductors of normally rated multi-core
connecting cables nor the PE connecting points of
normal terminal boxes are suitable for this purpose.
In these cases a sufficiently dimensioned parallel PE
conductor needs to be installed. This can then be
connected to the ground terminal positioned on the
motor enclosure.
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