METREL MI 3399, Инструкция с упражнениями

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Electrical Installation Safety Trainer AD 1 - MI 3399
51
Figure 2-6: Short circuit current between two Phase conductors
2.2.2.3 Voltage drop
During the Z
LINE
measurement the fuse before the measured circuit is the one
referenced to. When measuring Z
LINE
on the supply conductor, the fuse prescribed by
the electrical distributor is considered. When measuring Z
LINE
on the circuit the fuse
installed before that circuit is considered. The difference between both measurements
must not be greater than 3%.
After the reference impedance (Z
REF
) has been determined the actual voltage drop test
may be performed. The voltage drop is calculated as follows:
𝛥𝑈[%] =
(𝑍 − 𝑍
𝑅𝐸𝐹
) ∙ 𝐼
𝑁
𝑈
𝑁
∙ 100 < 3%
where:
ΔU – Voltage drop,
Z
– Measured line impedance,
Z
REF
– Reference line impedance,
I
N
– rated current of selected fuse,
U
N
– nominal voltage (see Table 2-1).
U
N
Input voltage range (L-N or L1-L2)
110 V 93 V <= UL-N < 134 V
230 V 185 V <= UL-N <= 266 V
400 V 321 V < UL-L <= 485 V
Table 2-1: Nominal voltage table