POWER FACTOR TIP-UP, CAPACITANCE/DISSIPATION FACTOR

Theory: Measurement of the ratio capacitance and the resistance within the insulation material. This is usually done at 25% and 100% of full line to ground voltage and the two quantities are subtracted to get the percentage difference. The result gives and indication moisture, contamination or voids in the insulation. See the following slides for more of an explanation.

Guiding Specification: IEEE 286, IEEE 1415Correction to: None specifically needed for this test, although

test is suggested at room temperature and at the same temperature if comparing trended results. Some conversions to a common temperature base can be done if trending is desired

Units of results: Percent % Typical results: 0.5 % to > 5% Tip up

POWER FACTOR TIP-UP, CAPACITANCE/DISSIPATION FACTOR

CONTINUEDAcceptance Criteria of Guiding Specification (IEEE

1415): < than 2% power factor and 1 % or less tip-up for motors rated 5 kV and less with a new epoxy/mica or polyester/mica based insulation system, up to 2 % tip up for reconditioned windings and up to 5% for older asphalt windings

Acceptance Criteria of ERS-E-001 Version # 7: Similar to the above specification

Other Notes: Trend over time is useful Temperature of winding and dew point should be noted at the

time of the test This will help normalize the measured values if trending is desired See the following slides for further explanation

POWER FACTOR TIP-UP, CAPACITANCE/DISSIPATION FACTOR

CONTINUED

1. Ratio between capacitance & resistance in material

2. Voltage & Current phase shifted 90 Degrees & current through insulation is capacitive in a perfect capacitor

3. Impurities and voids cause current to become more resistive

4. Power factor=Cosine of Theta

Theta (Θ)

POWER FACTOR TIP-UP, CAPACITANCE/DISSIPATION FACTOR

CONTINUEDReview of Right triangles:

SOHCOHTOA

Tan A=opp/adj=a/b

Example:A=3B=4C=5

POWER FACTOR TIP-UP, CAPACITANCE/DISSIPATION FACTOR

CONTINUEDActual cut & paste from a real test:

PARTIAL DISCHARGE/EMITheory: Partial Discharge (PD) is an electrical spark across an air

gap or void. There has to be a gap, and a potential of 3,000 Volt/mm or 76.2 Volts/mil across that gap for PD to occur. Surface discharge due to contamination could show up as PD when arcing occurs. EMI is related to PD in that PD emits a radio signal (RF). So an AM radio tuner is used to find the RF signals associated with PD. An EMI Sniffer is what Layne Gunter is experimenting with and helps to find the “localized” cause of the PD

Guiding Specification: IEEE 1434Correction to: A known wave function generated and a calibrating

capacitor discharging at a known rate to make IEC 60270 compliant. Otherwise, temperature of winding and dew point needs to be noted

Units of results: pF if IEC Compliant, mV if notTypical results: Varies (7-3,200 mV – non-IEC Compliance)

PARTIAL DISCHARGE/EMI CONTINUEDTesting Values, Graphs and Plots obtained: