Testing Principle of Low Frequency Method using in CTA-1000

CTA-1000 CT Analyzer compliance with standard <IEC60044> and <IEC61869>, and the standard basis for CT Analyzer measuring the excitation characteristics of iron cores by low frequency method is as follows:

From IEC standard, CT testing can be done in conditions lower in frequency than the rated to avoid secondary windings the risk of failing to allow the terminal voltage. The only requirement is that the core has the same size on the magnetic flux.

IEC60044-6 standard formula using in CTA-1000 CT Analyzer  for calculating the magnetic flux given by:

  Ψ(t)=∫[Uct(t)-Rct*Ict(t)]dt+Ψ0

Where,
  Rct: Secondary winding resistance
  Uct(t): Secondary winding terminal voltage
  Ict：Secondary current
  Ψo：The initial flux Alternation
  Ψ(t)： T the magnetic moment of the cross-linking

The definition of Core Voltage:
  Uc(t)=Uct(t)-Rct*Ict(t)

When the core voltage Uc(t) for the sinusoidal signal, core voltage RMS to meet:
  Ucrms=ω*Ψm/√2=2*Π*f*Ψm/√2=4.44*f*Ψm
where：
  f： For the sinusoidal signal frequency

As can be seen, the largest settlement in the same chain of magnetic flux Ψm, the core is proportional to voltage and frequency. Therefore, as long as the core has the same size on the magnetic flux, then the test CT can be lower than the rated frequency of the conduct, when the core voltage amplitude required to reduce the requirements, test power of ct analyzer to the secondary winding of the client voltage also be reduced accordingly. On the frequency of low-frequency test results can be rated after the conversion frequency in ct analyzer.
CTA-1000 CT Analyzer and its accessories are as follows:

 

By using low frequency method in the CTA-1000  CT Analyzer , the  ct analyzer gets some remarkable advantages as following:

1. The output voltage is low, Safety for testers and winding;
2. Tester has powerful functions and wiring is simple, and the testing process is very efficient;
3. Tester is portable with high precision.