Wat ass e Buchholz Relais a firwat ass et sou wichteg fir Transformator Schutz?

Ënnert de ville Schutzgeräter, déi a Kraafttransformatoren benotzt ginn, den Buchholz Relais gëtt allgemeng als ee vun de wichtegste Schutzmoossnamen fir Ueleg-ënnerdaucht Transformatoren ugesinn. Handelen als stille Erzéiungsberechtegten, et kann déi fréist Unzeeche vun internen Fehler entdecken an äntweren ier kleng Probleemer an deier Feeler eskaléieren, Equipement Schued, oder verbreet Stroumausbroch.

Mee wat ass genee e Buchholz Relais? Wéi funktionéiert et? A firwat gëtt et als onverzichtbar a groussen Ueleggefëllte Transformatoren ronderëm d'Welt ugesinn?

Loosst eis e méi no kucken.

Wat ass e Buchholz Relais?

E Buchholz Relais ass e Gas-aktuéierte Schutzapparat, deen am Päif installéiert ass, deen den Haapttransformatorbehälter an de Konservatortank vun engem Ueleg-ënnerdauchten Transformator verbënnt.

Erfonnt vum däitschen Ingenieur Max Buchholz an 1921, Dëse Relais ass speziell entwéckelt fir intern Transformatorfehler z'entdecken. Et iwwerwaacht kontinuéierlech d'Präsenz vu Gasen, déi duerch Isolatiounsofbroch generéiert ginn, partiell Entladungen, Wicklungsfehler, Iwwerhëtzung, an aner anormal Konditiounen, déi am Transformator optrieden.

Andeems Dir dës Warnschëlder fréi z'identifizéieren, de Buchholz Relais hëlleft schwéiere Schued ze verhënneren a verbessert allgemeng Transformator Zouverlässegkeet.

Installatioun Location: Firwat Positioun Matters

De Buchholz Relais gëtt tëscht dem Konservatortank an dem Haapttransformatortank installéiert, wéi ënnendrënner gewisen:

Conservator Tank
       │
       │  Connecting Pipe
 ┌──────────┐
 │ Buchholz │
 │  Relay   │
 └──────────┘
       │
       │
Main Transformer Tank

Dës Plaz ass kritesch well Gase generéiert duerch intern Feeler natierlech duerch d'Ueleg eropklammen an an de Konservatortank reesen. Andeems Dir de Relais direkt op dësem Wee setzt, et kann effektiv Feeler-Zesummenhang Gas Heefung an Ueleg Bewegung entdecken.

Wéi funktionnéiert e Buchholz Relais?

De Betribsprinzip vun engem Buchholz Relais baséiert op zwee verschidde Feelerbedéngungen: Gas Akkumulation an Ueleg Iwwerschwemmung.

1. Gas Akkumulation: Fréi Warnung fir kleng Feeler

Wann en Transformator kleng intern Probleemer erliewt wéi z:

• Isolatioun Alterung
• Deelweis Entladung
• Kär Iwwerhëtzung
• Los elektresch Verbindungen

den Isoléierueleg fänkt lues un ze zersetzen, produzéiert kleng Quantitéiten vu Gas.

Wéi dës Gase klammen a sech an der Relaiskammer accumuléieren, den Ueleg Niveau am Relais fällt. Dëst bewierkt datt den ieweschte Schwämm erof geet an den Alarmkontakt aktivéiert.

Op dëser Etapp:

✅ En Alarmsignal gëtt an de Kontrollraum geschéckt.

❌ Den Transformator funktionnéiert weider normal.

Dës fréi Warnung erlaabt Ënnerhalt Personal d'Thema z'ënnersichen an unzegoen ier et zu engem seriöse Feeler entwéckelt.

2. Ueleg Surge: Immediate Response to Major Faults

When severe internal faults occur, such as:

• Inter-turn winding short circuits
• Phase-to-phase faults
• Ground faults
• Heavy arcing

the pressure inside the transformer rises rapidly.

This sudden pressure increase creates a high-velocity oil flow toward the conservator tank. The oil surge pushes a flap or vane inside the Buchholz Relay, triggering the trip contact.

Op dëser Etapp:

✅ A trip signal is generated immediately.

✅ The circuit breaker disconnects the transformer.

✅ Further damage is prevented.

The entire process typically takes only milliseconds to a few seconds, significantly reducing the risk of catastrophic transformer failure.

Main Components of a Buchholz Relay

Although relatively simple in design, the Buchholz Relay contains several essential components:

Float System

Monitors oil level changes caused by gas accumulation.

Flap or Vane Mechanism

Detects sudden oil movement caused by severe faults.

Alarm Contacts

Operate during minor faults and send warning signals.

Trip Contacts

Operate during major faults and initiate transformer shutdown.

Gas Sampling Valve

Allows maintenance personnel to collect gas samples for diagnostic analysis.

Why Is the Buchholz Relay So Important?

1. Early Fault Detection

Many transformer failures begin as small internal defects that are difficult to detect through external monitoring.

Conditions such as:

• Partial discharges
• Localized overheating
• Insulation deterioration

often generate gases long before they become critical.

The Buchholz Relay acts as an early warning system, helping operators identify and resolve issues before serious damage occurs.

2. Protection of High-Value Assets

Power transformers represent a major investment. Large utility transformers can cost hundreds of thousands or even millions of dollars.

Without rapid fault detection and isolation, internal faults may result in:

• Burned windings
• Tank rupture
• Fire hazards
• Extended power outages

The fast-acting trip function of the Buchholz Relay helps minimize these risks and protect valuable equipment.

3. Improved Power Supply Reliability

Modern power systems require uninterrupted operation.

By detecting internal abnormalities at an early stage, the Buchholz Relay enables planned maintenance rather than emergency repairs, reducing unexpected outages and improving grid reliability.

4. Supports Dissolved Gas Analysis (DGA)

The gas sampling valve on the relay allows operators to collect fault gases for Dissolved Gas Analysis (DGA).

Different gases indicate different fault types:

This information helps engineers determine both the nature and severity of transformer faults.

Limitations of the Buchholz Relay

Despite its effectiveness, the Buchholz Relay is not a complete protection solution.

Applicable Only to Conservator-Type Transformers

Sealed transformers without conservator tanks cannot utilize a Buchholz Relay.

Cannot Detect External Faults

The relay does not respond to:

• External short circuits
• Lightning surges
• System overloads

Additional protection systems such as differential protection and overcurrent relays are required.

Requires Proper Installation and Maintenance

Incorrect installation or inadequate maintenance can compromise its performance.

Maintenance Recommendations

To ensure reliable operation, regular inspections should include:

• Visual condition checks
• Oil leakage inspection
• Alarm circuit testing
• Trip circuit testing
• Float and flap operation testing
• Gas sampling and DGA evaluation

A comprehensive inspection is generally recommended at least once per year.

Author

PDDN – Power Distribution & New Energy Solutions

PDDN specializes in transformers, Ënnerstatiounen, power distribution equipment, solar energy systems, Energie Stockage Léisungen, and integrated power infrastructure projects. Our engineering team is committed to providing reliable electrical equipment and technical expertise for utility, industrial, and renewable energy applications worldwide.