Digital Transformer Ratiometer DTR
®
Model 8510
35
AsinVT/PT,theCTtestmayberunasmanytimesasneededbypressing
theTESTbutton.
ThemeasurementrecordscanbesavedinManual or Auto mode as in
VT/PTmode.
TheCTremainsactiveuntilthecongurationischanged.Poweringthe
instrumentdownandturningitbackonwillnotchangetheTestType.
5.3 Tips for Making Precise Ratio Measurements
TheDTR
®
Model8510isdesignedforstep-downtransformers.Itsources
low voltage on the primary. It starts with a fraction of the nal source
voltageandchecksthesecondaryvoltage.
Ifitexceedstheprimarybyapre-determinedvalue,thesafetyfeaturestops
themeasurement.Therecommendedprocedureistoreversetheleadsin
thesecircumstancessothattheprimaryofthetransformerisconnected
totheHcablesandthesecondaryofthetransformerisconnectedtothe
Xcables.
CAUTION: It is important to check that the H cables are connected to
the primary side and the X cables are connected to the secondary side
of the transformer before the test begins.
• Alwaysverifytheintegrityofthecableconnectionsandreposition
theclipsasnecessaryforrobustandlow-resistanceconnections.
Inspectthetransformerterminalsfordielectriccoatings,fungus,dirt
or corrosion.
• Runningacontinuitytestbeforetheratiotestwillprovideauseful
waytocheckwindingsandconnections.
• Whentestingpolyphasetransformers,keepinmindthatinsome
cases,themeasuredratiosmustbemultipliedordividedby√3.
Referto§6forpolyphaseconnectiondiagramsandassociatedratio
equations.
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