What is the burden of the current input of PM800 series meters at rated current?
Issue
According to the PowerLogic PM800 Series Product Specifications Guide 63230-500-286A1 the burden of current input on each channel is less than 0.15 VA. The nominal current charted in the table is 5A AC.
According to the PowerLogic PM800 Series Product Specifications Guide 63230-500-286A1 the burden of current input on each channel is less than 0.15 VA. The nominal current charted in the table is 5A AC.
According to this, using the formula Z=(VA)/(I^2), the impedance comes to be 0.006 Ohm (=0.15/(5^2)). This number is much less than charted input impedance, 0.1 Ohm.
Product Line
PM800 series meter: PM820, PM850 and PM870.
PM800 series meter: PM820, PM850 and PM870.
Environment
The input impedance between I1+ and I1- or I2+ and I2- or I3+ and I3-.
The input impedance between I1+ and I1- or I2+ and I2- or I3+ and I3-.
Cause
The burden in the datasheet has not been calculated at nominal current.
The burden in the datasheet has not been calculated at nominal current.
Resolution
The hardware group has run series of tests where 10A was injected into the CT to calculate the impedance:
The results indicate that the impedance should read less than 1 mOhm (measured from the CT inputs @10A 60Hz).
From this we calculate the VA (burden) to be 0.025VA @ 5A (nominal current).
The hardware group has run series of tests where 10A was injected into the CT to calculate the impedance:
The results indicate that the impedance should read less than 1 mOhm (measured from the CT inputs @10A 60Hz).
From this we calculate the VA (burden) to be 0.025VA @ 5A (nominal current).