Transformer Oil Level Gauges

Introduction

Oil level gauges are critical monitoring instruments for oil-immersed power transformers, enabling real-time oil level indication, high/low oil level alarm, and remote monitoring. They are essential components to prevent transformer damage caused by oil shortage, overpressure, or leakage. This guide details two common types: the UHZ-01 float-type oil level gauge and the YZF-90~250 series oil level gauge, including their working principles, specifications, installation guidelines, and industry applications.

1. UHZ-01 Oil Level Gauge

Application

The UHZ-01 oil level gauge is designed for small and medium-sized oil-immersed transformers, oil storage tanks, and enclosed/open pressure vessels. It replaces traditional through-type glass tube gauges with the advantages of safety, visibility, reliability, and long service life.

Operating Conditions

Ambient temperature: -35°C ~ 55°C

Relative humidity: ≤ 90% (at 25°C)

Altitude: ≤ 2000m

Installation environment: No severe vibration or strong magnetic fields

Installation requirement: The gauge must be mounted vertically

Structure & Working Principle

Structure: Composed of a float, connecting rod, gauge body, magnetic steel, and pointer. The gauge body completely isolates the float and pointer, ensuring the reliability of the oil seal.

Working Principle: When the oil level in the oil storage tank rises or falls (due to temperature changes or other factors), the float rises or falls synchronously with the oil surface. The magnetic steel drives the pointer to rotate, clearly indicating the oil level status (high/normal/low).

Key Notes

Do not subject the gauge to strong impact.

Do not stretch or bend the connecting rod during installation or use.

If the sealing gasket fails to seal, check if the screws are tightened or if the contact surface between the mounting plate and the gasket is flat.

Installation Instructions

The gauge uses 25°C oil temperature as the reference for oil level. Adjust the oil level reading according to the actual oil temperature during installation.

The standard model has a maximum effective measuring range of 150mm. Custom ranges are available upon request.

Technical Specifications (UHZ-01 Series)

2. YZF-90~250 Series Oil Level Gauge

Overview

This oil level gauge is designed for transformer oil storage tanks, providing on-site direct indication and switch signal output for remote monitoring. It is an essential instrument for monitoring transformer oil levels.

Structure & Working Principle

Structure: Composed of three parts:

Display part: Pointer and dial

Alarm part: Magnet (or cam) and switch assembly

Transmission part: Pendulum, reversing gear, and magnetic coupling

Sensor part: Float (or floating ball) and oil tank diaphragm

Working Principle: As the oil level in the transformer oil tank rises or falls, the float moves up and down with the diaphragm, driving the pendulum to swing. The magnetic coupling transmits motion to the display part, rotating the pointer to show the oil level. When the oil level reaches the maximum or minimum position, the pointer triggers the alarm signal.

Model Explanation

YZF [ ] - [ ]

First digit: Environmental protection level (TH for three-proof)

Second digit: Specification (dial diameter)

Third digit: Design serial number

Fourth digit: Connecting rod structure (F = straight rod; S = telescopic rod)

Technical Parameters

Ambient temperature: -30°C ~ +115°C

Relative humidity: ≤ 90% (at 25°C)

Maximum oil temperature: ≤ 90°C

Installation environment: No severe vibration or shock

Indicating error: < 2.5% of full scale

Sealing performance: No leakage at 200kPa for 20 minutes

Protection class: IP55

Long-term stability: ≥ 10,000 operations

Switch capacity: AC 220V 5A; DC 220V 0.3A

Insulation resistance: 2000V, 1min

Key Notes

This gauge is a precision instrument. If a fault occurs, please contact the manufacturer directly. Disassembly by unauthorized personnel will void the warranty.

Avoid severe impact or long-term use in environments with severe vibration.

During transportation, separate the connecting rod from the diaphragm and hang it on the hook inside the oil tank.

The numbers on the dial are only relative positions, not absolute values.

Pre-Installation Check

Verify that the pointer movement corresponds to the float/connecting rod movement.

Check that the pointer rotates smoothly and freely.

Inspect the dial glass to ensure it is properly sealed.

3. Core Advantages of Transformer Oil Level Gauges

✅ Dual Monitoring Functionality: Both UHZ and YZF series provide visual on-site indication. The YZF series adds switch signal output for remote monitoring and automatic alarm.✅ High Reliability: Hermetic design with magnetic coupling ensures oil sealing, preventing leakage and moisture ingress.✅ Harsh Environment Resistance: With wide operating temperature ranges (-35°C ~ 55°C or -30°C ~ +115°C) and three-proof (moisture-proof, dust-proof, corrosion-proof) capabilities, suitable for outdoor substations.✅ Easy Installation & Maintenance: Vertical installation on the transformer tank top, with standard flange dimensions matching most oil storage tanks.✅ Long Service Life: Durable materials and wear-resistant components ensure stable operation for over 10,000 cycles.

4. Common Industry Applications

Distribution Transformers: Monitor oil levels to prevent overheating and insulation breakdown caused by oil shortage.

Power Transformers: Provide high/low oil level alarms to trigger power cuts or maintenance alerts.

Oil Storage Tanks: Used in power plants and substations to monitor bulk transformer oil storage levels.

Industrial Pressure Vessels: Applicable to various enclosed or open vessels requiring liquid level monitoring.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between UHZ-01 and YZF series gauges?

A: The UHZ-01 is a basic float-type gauge for visual indication only, suitable for small transformers. The YZF series adds high/low oil level alarm and remote monitoring functions, making it ideal for medium and large power transformers requiring automatic protection.

Q2: Can these gauges be installed horizontally?

A: No. Both gauges require vertical installation to ensure the float moves freely with the oil surface. Angled installation may cause inaccurate readings or jamming.

Q3: What should I do if the pointer does not move?

A: Check if the connecting rod is bent or stuck, if the float is damaged, or if there is strong magnetic interference nearby. If the issue persists, contact the manufacturer for calibration or replacement.

Q4: Are custom ranges available?

A: Yes. Custom ranges, dial sizes, and alarm configurations can be tailored to specific transformer models or application requirements.