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Abierto - Circuit Fault sa Secondary Side
Ang abierto - circuit sa secondary side mao ang typical nga fault sa low - voltage nga voltage transformers, nagpakita og abnormal nga voltmeter readings (zero/fluctuation), faulty nga power meters, buzzing noises, ug core overheating. Sa panahon sa abierto - circuited, ang secondary voltage mospike (walay secondary current aron mobalance sa primary EMF), nagsulob sa core saturation, flux distortion, ug potential overheating/damage.
Ang mga causa kabilin loose terminals, poor contact, o human error. Sa low - voltage systems, ang secondary side niconnect parallel sa meters/protection devices (high impedance, near no - load). Ang break/poor contact moporma og abierto - circuit—e.g., rusted 10kV substation terminals nimoogabierto - circuit, voltmeter errors, ug protection misoperation.
Arong pagtubag: Unang, disable ang misoperation - prone protections. Check joints/terminals (measure secondary resistance sukad multimeter). Repair abierto - circuit points safely. Temporarily short - circuit ang secondary sa test terminals (dili para sa long - term use).
Insulation Damage Fault
Ang insulation damage mao ang common, nagpuyo sa high - voltage fuse melting, internal discharge, overheating, o fire. Caused sa moisture, rust, dust, o mechanical damage (degrading insulation materials like epoxy resin, silicon steel, o paper).
Ang epoxy resin’s water absorption mogamit kaabot sa taas sa high humidity/temperature (95% RH, 65℃), dropping volume resistivity gikan sa 1.57×10¹⁵Ω·cm ngadto sa 5.21×10¹⁴Ω·cm. Dust ug vibration magaccelerate aging.
Example: Ang 10kV substation’s voltage transformer namatay tungod sa water ingress (poor sealing), nagreduce sa insulation resistance ug melting sa high - voltage fuse.
Prevention: Regular insulation tests (>1MΩ, 2500V megohmmeter for 10kV PTs). Keep equipment clean, ensure single - point grounding. Para sa damp transformers: mild cases gamiton hot oil circulation; severe cases need vacuum drying o insulation replacement.
Excessive Error Fault
Ang excessive error mokaon mismatched meter readings, metering deviations, ug protection misjudgments. Per JJG314 - 2010, errors must stay within limits for 25%–100% rated secondary load. Out - of - range loads (too high/low) cause errors.
Causes: Overloaded secondary, excessive conductor voltage drop, poor contacts, o harsh environments. E.g., long/small - cross - section 10kV secondary wires caused >0.5% metering errors.
Fix: Check secondary connections (ensure good contact). Measure wire length/cross - section; replace/shorten wires if needed. Adjust errors (replace if adjustment fails).
Mechanical Damage Fault
Ang mechanical damage (winding deformation, loose cores, broken shells) mokon sa improper transport, installation, o vibration. Iya nagharm sa accuracy ug nagaresulta sa partial discharge/insulation issues—e.g., 10kV transformer installation vibration loosened the core, causing noise ug errors.
Prevention: Gamiton shock - absorbing packaging (honeycomb cardboard + polyurethane foam) during transport (limit component displacement to <1mm). Install per specs, check structure regularly.
Multi - point Grounding Fault of the Secondary Circuit
Ang multi - point grounding mocaon neutral voltage shifts, protection misjudgments. Low - voltage systems require single - point grounding; multi - point grounding creates circulating currents.
Causes: Poor installation, damaged wires, o bad contacts. E.g., 10kV substation B/C phase auxiliary windings grounded together mocaon over - current, fuse melting, ug protection misoperation.
Fix: Identify ug remove extra ground points (ensure one ground). Check connections. Test resistance between UN ug the protection panel’s ground bar (≈0Ω indicates multi - point grounding).
