AEMC 8500 - 2 Product Features; Description

Digital Transformer Ratiometer DTR
®
Model 8500 5
CHAPTER 2
PRODUCT FEATURES
2.1 Description
The DTR
®
Model 8500 is a lightweight, rugged, portable digital transformer
ratiometer designed for onsite testing of power, potential and current trans-
formers. Operation of the Model 8500 is fully automatic. No user calibra-
tion,rangeselection,handcrankingortediousbalancingisrequired.
During each test cycle, the DTR
®
automatically checks for:
• H/Xleadreversal
• Continuityoftestedcircuits/windings
• Shortcircuitconditions(highcurrent)
Uponcompletionofatestcycle,theDTR
®
displays:
• Turns Ratio - the ratio of the primary to secondary voltage at the
transformer terminals due to test excitation
• Excitation Current - the RMS excitation current in the H winding
duetotestexcitationduringnegligibleloadingoftheassociatedX
winding
• Polarity-indicatesthepolarity(phase)ofXrelativetoH
Turns Ratio, Excitation Current and Polarity are useful parameters in diag-
nosing and predicting a variety of faults that occur in power, potential and
current transformers.
The Model 8500 will display the following messages:
• IncorrectLeadConnections
• H/XReversal(accidentalstep-upmisconnection)
• Short(excessexcitationcurrent)
• OpenCircuits
• CircuitContinuity
• LowBattery
The DTR
®
utilizes an advanced, low-voltage, step-down measurement
technique in which the high voltage “H” winding is subjected to test
excitation. This results in greater operator safety and the ability to test
a much wider array of transformer types and sizes.