Cirrus Logic AN362 - Manual (Page 7)

AN362
AN362REV1 7
4. Accuracy Test with Current Transformer CT, U
n
= 240V and I
b(max)
= 2.5(100A) at 50Hz
Taehwatrans TZ76V is used as the current sensor. The CT has the turn's ratio of 2500:1. Use 4Ω as the load
resistor. When the meter is applied with the maximum load current, I
max
= 100A, the secondary output voltage
is (100/2500) × 4 = 0.16 V
RMS
, which is below the maximum I-channel input range when setting the PGA for
current channel 1 (I1) to 10x.
High-pass filter (HPF) is enabled on the voltage channel: V1FLT[1:0] = ‘01’
High-pass filter (HPF) is enabled on the current channel: I1FLT[1:0] = ‘01’
Figure 6. Connection between Current Transformer CT and CS5480
CS5480
IIN 1-
IIN 1+
1KΩ
1KΩ
V+
V-
IIN1-
IIN1+
J1
CT
TZ76V
Current
4Ω
1KΩ
1KΩ
27nF
27nF