11.5 PT Burden Measurement
Description:
This application allows the user to perform an in service burden measurement of the PT circuit.
There are two different methods to measure the burden in the system using the PowerMaster
®
:
1. Burden Measure with Connections at Test Switch
2. Calculated Burden with Connections to Test Switch
For each method, the PowerMaster
®
measures the entire resistance in the circuit for each PT. If
a PT is selected in the Site Editor, the PowerMaster
®
will display a PASS or FAIL message on the
screen based on burden rating (VA). If a FAIL message is displayed, this means that the
measured resistance in the circuit exceeds the manufacturer’s stated burden rating. As
resistance increases, less secondary voltage is measured by the meter. If the meter does not
measure all available voltage, the likelihood of a billing error will occur.
Once an error is detected by the PowerMaster
®
, the technician should follow methods on
decreasing the actual burden. This normally consists of tightening down connections at the test
switch and/or PT secondary terminals. If a problem remains, the technician may consider
replacing the PT with a higher VA rating to validate resistance is within specification.
11.5.1 Burden Measure with Connections at Test Switch
This set of instructions is for when current connections are made at the PT while the voltage
connections are made at the test switch. The use of clamp-on probes (MN375 or MN353) is
required for measuring secondary current.
Rev 1.5 109
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