ABB FOCH, Hardware Manual, Page: 10 / 38

the nominal line-to-line voltage ( Un). To calculate the actual peak voltage value in volts
and d
u/dt value in volts per microsecond, multiply the values of the graph by the
supply voltage (
U
n
).
The values in the first graph are measured with an ABB d u/dt filter while the second
graph without any output filtering. The values in the second graph are only
representative. The actual unfiltered d
u/dt values depend on the drive type, and are
usually in the range of 1 to 5 kV/microsecond.
The voltage rise time can be calculated as follows: t = 0.8 ·
Û
LL
/(d
u/dt).
100 200 300
0.0
0.5
1.0
1.5
2.0
2.5
3.0
/---- (1/
µ
s)
U
n
---
u
--- -d-
t
-
d
l (m)
Û
LL
/
U
n
A
Û
LL
/
U
n
l (m)
d
u
/d
t
U
n
-------------(
1/ µ s
)
1.0
2.0
5.0
4.0
3.0
1.5
2.5
3.5
4.5
100 200 300
5.5
B
Drive with d u/dt filter A
Drive without d u/dt filter B
Motor cable length
I
Relative peak line-to-line voltage Û
LL
/ U
n
Relative d
u/dt value
(d
u/dt)/U
n
Note:
Û
LL
and d
u/dt values are approximately 20% higher with resistor braking.
Type designation label
The type designation label includes IEC and UL (NEC) ratings, appropriate markings
and the type designation and serial number, which allow identification of each filter.
An example label is shown below.
10 Operation principle