Lenze EDB9300UES User Manual
Page 78
Transport, Installation and Connection
BA8230
73
Notes:
1)
PVC insulated 3-phase cable 0.6/1 kV to DIN/VDE 0271.
Cables with a braided screen providing a high degree of cover (comparable to
control cables) are not required for supplying frequency inverters with regard to
the EMC characteristics. These cables increase the capacitive load on the inverter
so that it becomes necessary to reduce the cable lengths stated for NYCWY by
approx. 40 %. Repeated parallel connection of these types of cables to increase
the cross-section, if not stated expressly in
Table 23, is only permitted with a
proportional reduction in the lengths stated.
2)
At an inverter pulse frequency of 6 kHz the resulting permitted cable length is
reduced by 30 %.
3)
If very high control dynamics are required, e.g. an enclosed control surface of
≤
0.25 %/sec at a
±
50 % change in load at rated speed (VDI/VDE 2185), a direct
connection between the 8230 frequency inverter and the motor must be taken into
consideration during the design stage. The maximum voltage drop over the motor
cable may not exceed 1.75 %. This value also applies to lifting equipment. A 5 %
reserve in the mains voltage is to be taken into account with regard to the given
dynamic control characteristics over 95 % of the motor type point. In addition, if
necessary, the drive characteristics in the event of mains undervoltage are to be
taken into account
(IEC 34.1: Requirements concerning electronic equipment).
4)
The output choke is used with the cable lengths stated in order to reduce the
capacitive load caused by the motor cable and also reduces the voltage rate of
rise. With cable lengths <150 m the motors used must be designed for the
maximum voltage loads stated in this section under “Notes: Winding insulation”.
5)
Compliance with the motor insulation limits according to DIN VDE 0530 Part 1,
Supplement 2: 1991
Typically U
max
= 1000 V; du/dt = 500 V/
µ
s. Modern asynchronous motors for
frequency inverter supply possess very high reserves in the insulation system by
comparison to this limit.
The overall length is decisive in group drives or multiple motor supplies. The voltage
drop across motor cables should not exceed 1.75 %.
With lower dynamic drive requirements the guideline value for the voltage drop over
the motor cable is
≤
3.0 % (DIN 18015).
The cable lengths stated are maximum values. No increase in the cross-section to
reduce the voltage drop over long motor cables has been taken into account and
should be determined if necessary, taking the motor power factor into consideration.
Voltage drop e [%]:
(
)
ϕ
∗
+
ϕ
∗
∗
∗
∗
=
sin
X
cos
R
U
10
I
3
e
I
U
Linked voltage [V]
I
Current load [A]
l
Supply length [m]
R
Resistance [
Ω
/km]
X
Inductive resistance [
Ω
/km]
1)
1)
The inductive voltage drop should be taken into consideration particularly with
cable cross-sections A
≥
50 mm².
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