UNI-T UT528AU Portable Appliance Tester (PAT)

The UNI-T UT528AU Portable Appliance Tester (PAT) is a dedicated electrical safety testing instrument designed for checking portable electrical appliances, Class I and Class II equipment, extension leads, and IEC power cords. It combines several essential safety tests into a compact battery-powered unit and provides automatic test sequences with clear PASS/FAIL results, making it suitable for routine electrical safety inspections and maintenance environments.

The UT528AU performs earth continuity, insulation resistance, leakage current, cord wiring, and phase tests. For Class I appliances, the earth continuity test checks the resistance of the protective earth connection using a test current of more than 200mA and a nominal 5V DC test voltage. The measurement range extends from 0.00Ω to 19.99Ω, with an accuracy of ±(5%+2). The instrument also provides configurable PASS limits for earth continuity, allowing the tester to evaluate whether the protective earth connection falls within the selected acceptable range. 

For insulation testing, the UT528AU supports selectable 250V and 500V DC test voltages. The insulation resistance display range is 0.20MΩ to 19.99MΩ, with an accuracy of ±(5%+2). The lower 250V test setting is useful when testing equipment or leads for which a 500V insulation test may not be appropriate, while the 500V setting provides the standard higher-voltage insulation test used for many appliance applications.

The instrument also performs leakage current testing over a range of 0.10mA to 10.5mA. This test uses a 50Vrms, 50Hz AC test signal according to the UT528AU specifications. In addition, the built-in cord test can identify wiring conditions such as correct wiring, open circuits, short circuits, and reversed wiring. A phase test can identify correct Live-Neutral-Earth relationships as well as faulty earth or neutral conditions when connected to a suitable mains supply.

One of the practical advantages of the UT528AU is its automatic test sequence. After selecting the appropriate appliance category, the tester performs the required measurements and presents the results and final PASS/FAIL status. It also includes a lead nulling function, which compensates for resistance introduced by the earth test lead, helping prevent the lead itself from unnecessarily increasing the measured earth-bond resistance.

The UT528AU is also equipped with a dedicated setting for extension leads longer than 30m, making it more suitable for testing longer power cables. Its large 136 × 47mm LCD, low-battery indication, and automatic power-off function support practical field use. The instrument is powered by six 1.5V C-size R14/LR14 batteries and has a compact 210 × 178 × 90mm housing with a net weight of approximately 970g.

With its combination of automated safety tests, selectable insulation test voltage, earth continuity measurement, leakage testing, cord verification, and portable battery-powered operation, the UNI-T UT528AU is suitable for technicians and service organizations performing repetitive electrical safety inspections on portable equipment and power leads.

Features

• Portable PAT electrical safety tester

• Automatic test sequences with PASS/FAIL indication

• Tests Class I and Class II appliances

• Supports extension lead and IEC cord testing

• 250V/500V selectable insulation testing

• Earth continuity testing with >200mA test current

• Leakage current measurement

• Cord wiring and polarity testing

• Phase testing for mains wiring

• Built-in earth lead nulling function

• Additional setting for extension leads over 30m

• Large 136 × 47mm LCD

• Battery powered for field testing

• Low-battery indication and auto power-off

• Compact and portable design

Specifications

• Brand: UNI-T

• Model: UT528AU

• Product Type: Portable Appliance Tester (PAT)

• Application Classes: Class I / Class II / Extension Leads

• Earth Continuity Range: 0.00Ω–19.99Ω

• Earth Continuity Accuracy: ±(5%+2)

• Earth Continuity Test Current: >200mA

• Earth Continuity Test Voltage: 5V DC nominal

• Insulation Resistance Range: 0.20MΩ–19.99MΩ

• Insulation Accuracy: ±(5%+2)

• Insulation Test Voltage: 250V / 500V DC

• Insulation Test Current: >1mA at R = 500kΩ

• Short-Circuit Test Current: <3mA

• Leakage Current Range: 0.10–10.5mA

• Leakage Accuracy: ±(5%+2)

• Leakage Test Voltage: 50Vrms

• Leakage Test Frequency: 50Hz AC

• Cord Test: Correct wiring / open circuit / short circuit / reversed wiring

• Mains Input: 220V AC ±10%

• Display: LCD, 136 × 47mm

• Power Supply: 6 × 1.5V C batteries (R14/LR14)

• Auto Power Off: Yes

• Low Battery Indicator: Yes

• Dimensions: 210 × 178 × 90mm

• Weight: Approximately 970g

• Color: Red and grey

Applications

• Portable appliance safety testing

• Class I appliance inspection

• Class II appliance inspection

• Electrical equipment maintenance

• Extension lead testing

• IEC power cord testing

• Earth continuity verification

• Insulation resistance testing

• Leakage current testing

• Electrical workshop safety inspections

• Service and maintenance departments

• Commercial equipment safety checks

• Field electrical safety testing

• Periodic appliance inspection programs