3.9 Using a Current Sensor
107
Using an external CT
Usage example
Configure the instrument as follows:
Current sensor type: TYPE1
CT ratio: 200 (current sensor’s CT ratio of 20) × (external CT’s CT ratio of 10)
Current measurement range: 10 kA (shown as 50 A range on the instrument’s panel)
The current measured value (display value) on the instrument will be [7,800 kA].
If energized components are exposed when connecting the current sensor, exercise
care not to touch them or the CT. Doing so may result in electric shock, bodily injury,
or a short-circuit accident.
When using an external CT, avoid open-circuiting the secondary winding. If current
flows through the primary when the secondary is open, high voltage across the sec-
ondary could present a dangerous hazard.
• The external CT’s phase different could introduce a significant error component into power measurement.
For more accurate power measurement, use a CT with a small phase error in the frequency band used by
the circuit.
• When using an external CT, ground the CT’s secondary negative terminal to ensure safety.
Measured current 7,800 A (7.8 kA)
Current sensor 9669 Clamp on Sensor (rated current: 1,000 A AC)
External CT 10:1
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