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IM 2041-01
(2) 電流が定格値をこえる場合の単相電力測定
Fig. 2-3 のように電流回路に，計器用変流器（CT）を接続します。
負荷電力 (Watt) ＝計器の読み×乗数×変流比
(3) 電圧が定格値をこえる場合の単相電力測定
Fig. 2-4 のように電圧回路に，計器用変圧器（VT）を接続して測定し
ます。
負荷電力 (Watt) ＝計器の読み×乗数×変圧比
(4) 電圧，電流ともに定格値をこえる場合の単相電力測定
Fig. 2-5 のように電圧回路に VT を，電流回路に CT を接続して測定し
ます。
負荷電力 (Watt) ＝計器の読み×乗数×変圧比 × 変流比
＜計算例＞
計器使用レンジ：
120 V, 5 A
乗 数：
5
計器指示：
100
変圧比：
6,600/110 V
変流比：
50/5 A
6600
110
50
5
×
= 100 × 5 ×
= 300 000 watt (W)
= 300 kwatt (kW)
負荷電力
2. Single-phase power measurement where the current exceeds its
rated value
Connect a current transformer (CT) to a current circuit as shown in
Figure 2-3.
Measured power (watt)
= indicator reading × range multiplier × CT ratio
3. Single-phase power measurement where the voltage exceeds its
rated value
Connect a voltage transformer (VT) to a voltage circuit as shown in
Figure 2-4.
Measured power (watt)
= indicator reading × range multiplier × VT ratio
4. Single-phase power measurement where both the voltage and the
current exceed their rated values
Connect a VT to a voltage circuit and a CT to a current circuit as
shown in Figure 2-5.
Measured power (watt)
= indicator reading × range multiplier ×
VT ratio × CT ratio
Example:
Instrument terminals connected:
120 V, 5 A
Range multiplier:
5
Indicator reading:
100
VT ratio:
6600/110 V
CT ratio:
50/5 A
Measured power (watt) = 100 × 5 × (6600/110) × (50/5)
= 300 000 watts (W)
= 300 kilowatts (kW)
Summary of Contents for 2041
Page 21: ...Printed in China ...
