Siemens 9700, Руководство по установке, Страница: 20 / 45

32:(50(7(5,167$//$7,21$1'%$6,&6(783
Current Input Specifications
Specification Value
Overload 15 Amps continuous, 300 Amps for 1 second, non-recurring
Impedance 2 m
Ω
Burden 0.0625 VA @ 6.25 Amps
Overrange Capability
The 1 Amp and 5 Amp phase current inputs provide 25% overrange
capability that allows current readings to be accurately displayed up to
125% of full scale. For example, if the CT Primary setup register in the
Power Meter module has been set at 2000A full scale, the 9700 Power Meter
allows for readings up to 2500A.
The 1 Amp and 5 Amp phase current inputs also allows for up to 2000% of
full scale for a maximum duration of 1 second. This provides a 20X fault
capture capability. The 10 Amp phase current inputs on revenue meters
allow for up to 1000% of full scale for a maximum duration of 1 second,
providing a 10X fault capture capability.
Using Current Transformers
The 9700 Power Meter is compatible with CTs with 1 Amp, 5 Amp or 10
Amp full scale secondaries (depending on the options purchased). The
current input ratings of all three-phase inputs and the I4 input are
equivalent.
The CT secondary should have a burden capacity greater than 3 VA. The
length of the CT cabling should be minimized because long cabling
contributes to inaccuracy. Also, the CT burden rating must exceed the
combined burden of the 9700 Power Meter plus cabling and any other
connected devices (burden is the amount of load being fed by the CT,
measured in Volt-Amps).
Overall accuracy depends on the combined accuracy of the 9700 Power
Meter, the CT, and the PTs (if used).
I4 Current Input Connection
I4 is typically used to measure the current flow in the neutral or ground
conductor. Connection is optional. The secondary rating of the CT
connected to the I4 input must be identical to that of the three phase current
inputs.
The primary rating for the CT connected to the I4 input can be different from
the three phase inputs, since the I4 input scaling can be programmed
independently.
2
38)
Refer to the 9700 Power
Meter User’s Guide for
Revenue Metering CT and
PT selection.