SEW-Eurodrive MOVIDRIVE compact MCH41A, System Manual

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System Manual – MOVIDRIVE® compact Drive Inverters
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Overload capacity of the inverter
Project Planning
Overload capa-
city in seconds This is the overload capacity that corresponds at the most to a quarter of the heat sink
time constant (0.25 T). The overload usually lasts a few seconds. In this time range, the
curve is almost linear and the overload capacity can be determined as follows:
Overload time t
1
< 0.25
×
T
→
determine using a formula
Formula
At overload times t
1
< 0.25 x T, you can calculate the overload capacity using the follow-
ing formula:
t
2
> k
×
t
1
k = overload factor
The values for overload factors k are given in the following tables, depending on the sup-
ply voltage V
1
, ambient temperature
ϑ
and cycle frequency f
PWM
.
Example Example with MOVIDRIVE
®
MC_4_A0055 (size 2):
• Operation with supply voltage V
1
= 3
×
AC 400 V, ambient temperature
ϑ
= 40 °C
and cycle frequency f
PWM
= 4 kHz.
• Rated unit current I
N
= AC 12.5 A and continuous output current I
D
= 125 %
×
I
N
=
AC 15.6 (
→
Figure 63)
• Overload time t
1
= 30 s = 0.1
×
T
• Low-load current I
out 2
= 6 A = 0.4
×
I
D
→
k = 0.778
• The low-load time must be t
2
> k
×
t
1
> 0.778
×
30 s > 23.34 s.
For overload times t
1
< 0.25
×
T use the formula t2 > k
×
t
1
to ascertain the overload
capacity. The following tables show the overload factor k for various low-load currents.
For your additional information, we have included the value depending on I
N
(at f
A
> 2
Hz) in addition to the overload current.
MC_4_A, sizes 1-5
overload capacity
at 400 V / 25 °C
MC_4_A, sizes 1-5
overload capacity
at 400 V / 40 °C
Cycle
frequency
f
PWM
Continuous
output current
I
D
(f
A
> 2 Hz)
Overload current
I
out 1
(at f
A
> 2 Hz)
Overload factor k at low-load current I
out 2
=
0 0.2
×
I
D
0.4
×
I
D
0.6
×
I
D
4 kHz 125% I
N
120% I
D
(= 150 % I
N
) 0.411 0.538 0.778 1.407
Cycle
frequency
f
PWM
Continuous out-
put current I
D
(f
A
> 2 Hz)
Overload current
I
out 1
(at f
A
> 2 Hz)
Overload factor k at low-load current I
out 2
=
0 0.2
×
I
D
0.4
×
I
D
0.6
×
I
D
0.8
×
I
D
4 kHz 144 % I
N
104 % I
D
(= 150 % I
N
) 0.085 0.107 0.145 0.226 0.508
8 kHz 112 % I
N
114 % I
D
(= 128 % I
N
) 0.314 0.408 0.582 1.016 4.160
16 kHz 78 % I
N
110 % I
D
(= 86 % I
N
) 0.235 0.303 0.427 0.720 2.324
Cycle
frequency
f
PWM
Continuous out-
put current I
D
(f
A
> 2 Hz)
Overload current
I
out 1
(at f
A
> 2 Hz)
Overload factor k at low-load current I
out 2
=
0 0.2
×
I
D
0.4
×
I
D
0.6
×
I
D
4 kHz 125 % I
N
120 % I
D
(= 150 % I
N
) 0.411 0.538 0.778 1.407
8 kHz 100 % I
N
125 % I
D
(= 125 % I
N
) 0.678 0.928 1.473 3.639
16 kHz 68 % I
N
126 % I
D
(= 86 % I
N
) 0.676 0.922 1.448 3.438