Sêweşên Dûr Ênîyên Tap Changer (Bê Sêwê)

I. Xallên ji bo Tap Changers (De-energized)

1. Asûdan Berdewamî

• Pêşazîna seran tap changer di derbarê pêşaziya seran de ne ku bêkariyê, pêşaziya seranek rolera nayê herêmek, an destûr mekanîkî ya tabaka qulbardar li ser hêsan û werdigirina vebiyên paqij—yan di serkirinê de tap changer werdigire.

• Pêşaziya seran bi malper, an pêşaziya seran/welding rastên, ne ku bêkariyê di serkirinê de dîn da xalasî.

• Hilbijartina nayê saz di serkirinê de, ku wereca kirina berdewamî û werdigirina.

• Berdewamîya seran derbarê sê cihê yana destûrîya elektrikî ya materyalan parastî ne ku bêkariyê, ku di serkirinê de xalasîya seran di navcheyê de werdigire.

2. Bajarandina Xallê

Operatoran divê lîsteya mal perde bikin ji bo analîza gas chromatography, ber bi guhertinên dîn, bihat, dewe, sath mal, reng mal, û çavkanîya nayê seran, bi tenê ku bêtirîna xallê û amala kerda ser ast.

II. Xallên ji bo On-Load Tap Changers (OLTC)

1. Girîja Mal ji Kompartimenta Mal OLTC

Asûdan:

• Vana girîja di binê tanka OLTC de ne ku bêkariyê, ku mal ji kompartimenta OLTC û tanka transformatora sereke girîje.

• Berdest bimîna nayê seran an materyalan parastî ne ku bêkariyê di navcheyê de.

• Parastina nayê seran di ser êndaza central drive shaft de.

Bajarandina:
Tap changer ji kompartimenta mal hatine, kompartimenta mal hatine rakirin û sedra, ewa hilbijareka girîjê—sazîsa seran tap lead bolts an êndaza rotating shaft seals—û kerda ser ast.

2. Transition Resistors Broken or Loose

Asûdan:
Ger resistor transition piştre broken be û hilbijarta tap change bikin, dîna load current hatine girîjîn. Bihati full phase voltage di navcheyê de di navcheyê de, ku wereca:

• Berdewamîya gap resistor,

• Arcing intense di navcheyê de seran moving û fixed contacts,

• Xalasîya navcheyê di navcheyê de seran tap positions, ku hewce dikin werdigirina high-voltage winding tap segments.

Bajarandina:
Di demê nirxandinê de transformatora, her resistor transition bi tenê kontrol bikin ji bo danayê mekanîkî, los, an pêşaziya seran nayê seran, bi tenê ku bêtirîna overheat û werdigirina di serkirinê de.

3. Overheating of Tap Changer Contacts

Asûdan:
Veguhestina dîn voltage regulation wereca erodasyon elektrikî, werdigirina mekanîkî, û danayê seran. Di transformatoran bi dîn load currents:

• Joule heating wereca zêdetirina elasticity contact spring, ku bêtirîna pêşaziya seran,

• Resistance contact wereca zêdetirina, ku wereca zêdetirina heat,

• Ev wereca zêdetirina oxidation, corrosion, an deformation mekanîkî di navcheyê de seran, ku wereca thermal cycle vicious.

Bajarandina:
Pêş di commissioning de, test DC resistance bikin ji bo hemî tap positions. Di demê nirxandinê de hood-lift, kontrol integritiya plating contact û measure contact resistance. Ji bo danayê seran oil films an oxides, manually cycle the tap changer through multiple positions to ensure clean, firm contact.

4. Tap Changer "Run-On" (Continuous Operation)

Asûdan:

• Malfunction AC contactors (e.g., oil contamination, residual magnetism causing delayed de-energization) or faulty sequence switches.

• Unreliable AC contactors or micro-switches; loose screws or insufficiently long stop tabs on the tap changer mechanism.

Bajarandina:
Inspect contactors for sticking or delay; verify sequence switch logic. Realign components, use contactors with lower residual magnetism, or add a capacitor in series to suppress residual flux. Clean oil/contaminants from contactors and tighten all loose fasteners.

5. Tap Changer Exceeding Limit Positions

Asûdan:

• Rust on mechanical limit screws, rendering them ineffective in stopping shaft rotation.

• Insufficient height of positioning blocks, failing to trigger the electrical limit switch even at extreme positions.

Bajarandina:
Manually adjust upper/lower limit blocks and verify that position indicators match actual tap settings. If mismatched, disconnect the motor drive, manually crank the tap changer to a mid-position, then re-engage electric control.

6. Tap Changer Failure to Operate (Refusal to Switch)

Asûdan:

• Excessive or insufficient spring tension in the fast-acting mechanism (leading to breakage or sluggish action).

• Loose flexible connectors; overly tight sealing between the central shaft and oil compartment base, preventing full insertion of contacts.

Bajarandina:
Check for incomplete engagement between motor drive and tap changer:

• Verify interlock switch continuity and spring reset.

• Inspect for poor contact between fixed and moving contacts.
  If failure occurs in both directions, focus on:

• Reset status of manual crank interlock switch,

• Contact integrity of control switches,

• Normalcy of three-phase power supply.
  For delayed or incomplete switching, investigate:

• Weakened, fatigued, or broken energy-storage springs,

• Mechanical binding.
  Repair or replace faulty mechanical components or springs as needed.