Engineering
10/05 AWB8230-1541GB
18
Connection to power supply
The DF51 frequency inverters can not be used in every network
configuration without limitations (network configuration
according to IEC 364
-3).
Mains configurations
Networks with earthed centre point (TT/TN networks):
• DF51 frequency inverters can be used without limitations in TT
and TN networks. The ratings of the DF51 frequency inverters
must, however, be observed.
Networks with isolated centre point (IT networks):
• The use of DF51 frequency inverters in IT networks is only
permissible to a limited extent. In this case, a suitable device
(isolation monitor) to monitor earth faults and isolates the
frequency inverter from the mains must be used.
Mains voltage, mains frequency
The ratings of the DF51 frequency inverters cover European and
American standard voltages:
• 230 V, 50 Hz (EU) and 240 V, 60 Hz (USA) for DF51-320 and
DF51-322,
• 400 V, 50 Hz (EU) and 460 V, 60 Hz (USA) for DF51-340
The permitted line voltage range is:
• 230/240 V: 180 V – 0 % to 264 V + 0 %
• 380/460 V: 342 V – 0 % to 528 V + 0 %
The permissible frequency range is 47 Hz –0 % to 63 Hz +0 %.
The motor rating to mains voltage assignments are listed in the
appendix, paragraph “Technical data”, page 189.
Interaction with p.f. correction equipment
The DF51 frequency inverters absorb only a small fundamental
reactive power from the AC supply. Compensation is therefore
unnecessary.
Fuses and conductor cross-sections
The fuse ratings and cable cross-sections required for the network
connection depend on the rating of the frequency inverter and the
drive’s operating mode.
The recommended fuses and their assignment to the DF51
frequency inverters are listed in the appendix, paragraph “Mains
contactors”, page 210.
The national and regional standards (for example VDE 0113,
EN 60204) must be observed and the necessary approvals (for
example UL) at the site of installation must be fulfilled.
When the device is operated in a UL
-approved system, only
UL
-approved fuses, fuse bases and cables must be used.
The leakage currents to earth (to EN 50178) are greater than
3.5 mA. The connection terminals marked PE and the enclosure
must be connected to the earth circuit.
Warning!
Use only components (cables, FI switches, chokes, filters
and contactors) that match the frequency inverter’s rated
values. Otherwise there is a danger of fire.
h
If many frequency inverters with a single-phase supply are
connected to the same supply network, they should be
distributed symmetrically over all three phases and the
load placed on the common neutral connection (mains
r.m.s. current) must be taken into account. If necessary,
the cross-section of the neutral pole must be increased, if
it conducts the total current of all single-phase devices.
Caution!
In the event of an earth fault in an IT system, the
capacitors of the frequency inverter which are switched to
earth are subjected to a very high voltage, Therefore, safe
operation of the frequency inverter cannot be guaranteed.
To overcome this problem,fit additional isolating
transformer to the frequency inverter’s supply and earth
the transformer’s secondary side at its centre point to
form, in effect, an individual TN network for the frequency
inverter.
Caution!
Operate DF51 series frequency inverters on mains with
p.f. correction equipment only when this equipment is
damped with chokes.
Caution!
The voltage drop under load conditions should be
considered when selecting the cable cross-section.
Compliance to further standards (for example VDE 0113,
VDE 0289) is the responsibility of the user.
Caution!
The prescribed minimum cross-sections for PE conductors
(EN 50178, VDE 0160) must be observed. Use a PE
conductor whose cross-section is as least as large as the
terminal capacity of the power terminals.
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