MI 2892 Power Master
Recording Practice and Instrument Connection
123
Measuring range: 100%
Current transformer:
Prim: 100 A
Sec: 5 A
Current clamps:
A1122 (5A/1V)
100 A
100A load feeding
Load
Instrument display:
Irms = 100 A
Current Transformer:
600A : 5A
Clamp Selected: A 1122
Clamp Range: 5 A
Figure 4.20: Current clamps selection for indirect current measurement
Over-dimensioned current transformer
Installed current transformers on the field are usually over-dimensioned for “possibility to add new
loads in future”. In that case current in primary transformer can be less than 10% of rated transformer
current. For such cases it is recommended to select 10% current range as shown on figure below.
Figure 4.21: Selecting 10% of current clamps range
Note that if we want to perform direct current measure with 5 A clamps, primary transformer ratio
should be set to 5 A : 5 A.
WARNINGS !
The secondary winding of a current transformer must not be open when it is on a live circuit.
An open secondary circuit can result in dangerously high voltage across the terminals.
