01/02 AWB8230-1415GB
Selection criteria
11
Features of the frequency inverters
The DV6 frequency inverters convert the voltage and frequency of
an existing three-phase supply to a DC voltage and use this
voltage to generate a three-phase supply with adjustable voltage
and frequency. This variable three-phase supply allows infinitlely
adjustable speed control of three-phase asynchronous motors.
a
Supply through an interference suppressor
Mains voltage
V
LN
(EU-rated voltages):
3-phase 400 V AC, 50/60 Hz
b
The bridge rectifiers convert the AC voltage of the electrical supply to
a DC voltage.
c
The DC link contains a charging resistor, smoothing capacitor and
switched-mode power supply unit. It enables coupling of the DC bus
voltage and the DC current supply:
DC bus voltage (
V
ZK
) =
W
2
x
mains voltage (
V
LN
)
d
IGBT power inverter:
The power inverter converts the DC voltage of the internal DC link to
a variable three-phase alternating voltage with variable frequency. In
conjunction with an external braking resistor, the braking transistor
allows braking of motors with a high moment of inertia or during
extended regenerative operation.
e
Output voltage (
V
2
), motor connection:
three-phase, variable AC voltage, 0 to 100 % of the input voltage
(
V
LN
)
Output frequency (
f
2
):
variable frequency, 0 to 400 Hz
Output rated current (
I
2N
):
2.5 to 260 A with about 1.5 times the starting current for 60 s, with a
switching frequency of 5 kHz and at an ambient temperature of 40 °C
Motor connection, assigned shaft output (
P
2
):
0.75 to 132 kW at 400 V
f
Programmable control section with keypad and interface
Selection criteria
Select the frequency inverter according to the rated current of the
motor. The rated output current of the frequency inverter must
however, be greater than or equal to the rated current of the
motor.
The following drive data is assumed to be known:
• Type of motor (three-phase asynchronous motor)
• Mains voltage = supply voltage of the motor (e.g. 3 ~ 400 V)
• Rated motor current (guide value, dependent on the circuit type
and the supply voltage)
• Load torque (quadratic, constant, with 1.5 times the starting
torque)
• Ambient temperature (maximum temperature 40 °C).
The rated output current of the frequency inverter can be found in
the technical data in the appendix from Page 187.
Figure 5:
Function chart of the frequency inverter
a
b
c
d
f
e
M
3
˜
h
h
If several motors are connected in parallel to the output of
a frequency inverter, the motor currents are subject to
vector addition, i.e. the active in-phase current and reac-
tive current components are added separately. When you
select a frequency inverter, make sure that it can supply
the total resulting current.
h
If you connect a motor to an operational frequency
inverter, the motor draws a multiple of its rated current.
When you select a frequency inverter, make sure that the
starting current plus the sum of the currents of the
running motors will not exceed the rated output current of
the frequency inverter.
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