2. Installation of the frequency converter
2. Installation of the frequency converter
2.1. Connection of a power circuits
The frequency converters of the MFC710 type are electrical devices intended for control rotational speed of
asynchronous motors. This adjustment is made by changing the frequency and amplitude voltage at the output of the
converter.
The MFC710 converter is supplied from the three-phase network through terminals L1, L2, L3. In some implementations
there is a need to connect an auxiliary power supply intended to supply internal fans.
Fig. 2.1 shows a diagram of power circuits connections.
Fig. 2.1 - Connection of power circuits to MFC710 converter
The cross-sections of the cables and the type of the line choke should be selected depending on the load current.
The required fuses are shown in Table 0.2, the required cross-section values are presented in the table 2.1.
Table 2.1 - Long-term current load of copper wires with PVC insulation in tempe40
o
C on the
example of the cable HELUKABEL TOPFLEX-EMV-3 PLUS-2YSLCY-J 600/1000 V
No.cores x
cross-sec.
[mm
2
]
Power ratings
with 3 loaded cores
*)
[A]
No.cores x
cross-sec.
[mm
2
]
Power ratings
with 3 loaded cores
*)
[A]
3x1,5 + 3G 0,25
15
3x50 + 3G 10
146
3x2,5 + 3G 0,5
22
3x70 + 3G 10
180
3x4 + 3G 0,75
29
3x95 + 3G 16
217
3x6 + 3G 1
38
3x120 + 3G 16
254
3x10 + 3G 1,5
53
3x150 + 3G 25
291
3x16 + 3G 2,5
71
3x185 + 3G 35
332
3x25 + 3G 4
93
3x240 + 3G 42,5
394
3x35 + 3G 6
117
3G — yellow-green PE protective conductor (PE protective conductor is divided into 3 conductors — figure 2.2)
*) Load capacity converted for ambient air tempe 40
0
C (coefficient of 0.87).
Frequency converter MFC710 type with OP-11 control panel. TWERD Power Electronics
15
Fig. 2.2 - HELUKABEL
TOPFLEX-EMV-3
PLUS-2YSLCY-J
600/1000 V
PE
PE
PE
MFC710
L1
L2
L3
+BR
(+DC)
2)
Dynamic braking resistor
(option)
Overcurrent
protection
Power switch
PE
L1
L2
L3
PE
U
V
W
PE
Shield cable recommended
- Do not use any contactors between
converter output and motor!
- Output voltage can be measured
correctly only with an electromagnetic
voltometer!
-BR
(BR)
2)
ATTENTION!
Shown circuit has terminals for
illustration only and does not show their actually
position on the drive
1)
+BR(+DC), -BR(BR) connectors are only present in frequency converters ready to work with the breaking resistor
(this converters are equipped with breaking transistors - frequency converters at 18.5kW and below are equipped
as standard with breaking transistor, frequency converters at 22 kW and above are assembled in breaking
transistor optionally).
Attention:
frequency converters also can have +DC, -DC connectors. These are connectors of
internal DC circuit.
Do not connect breaking resistor to this connectors!
2)
Marks used for converters 22kW and above.
3)
Need to connect the power supply of internal fans on frequency converters with additional terminals
(inverters: 30 kW and 37 kW, 45..75kW produced until May 2016, the others depending on the version).
4)
A typical external supply voltage is 230V AC. Optionally, it can be 3x400V AC or other according to individual orders.
For this reason, depending on the version, there can be various power cords numbers and their markings.
5)
For rated power 5.5 kW and above 3 phase choke is recommended.
6)
Frequency converters 450kW and above have 6 input clamps and are prepared to work with 12-pulse input system.
7)
In a high power inverters can occur DC terminals: +M,+D. Depending on the individual settings, please connect a
choke, or do short-out by jumper.
1)
M
~
U
V
W
PE
L
N
6)
6)
6)
5)
M
ai
n
p
o
w
er
s
u
p
p
ly
A
u
x
il
ia
ry
p
o
w
er
su
p
p
ly
4)
L
N
3)
+M
+D
7)
