UNI-T UT502A - User Manual

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UT502A Insulation Resistance Tester is designed with brand-new

design and combination of massive integrated and digital circuits; it

can measure insulation resistance, low resistance, AC voltage, etc,

and enjoys high degree of accuracy, stable performance, easy

operation and reliability. It is used for insulation resistance

measurement for insulation materials and various kinds of electric

equipments such as transformer, electric machines, cables, switches,

electrical appliances, a ideal tool for electric equipment maintenance,

testing and inspection.

2. Safety Information

The instrument is designed and manufactured in compliance with

IEC61010 standard. The manual covers safety information related to

the safe operations and conditions of the instrument. please read

carefully before using the instrument.

Warning

Use always as specified in the manual, and keep it for future use.

conditions and actions that may cause serious or

fatal damage.

Alerts users to avoid electric shock.

conditions and actions that may cause damage to

the instrument or affect accurate measurement.

voltage over 750VAC.

leads

When test leads are shorted and connected to the instrument, do

not press TEST key.

during test.

Do not touch the tested line during insulation measurement.

Eg: the

instrument was damaged or had exposed metal.

discharged.

between test leads

lead

low battery indicator shows If

properly.

3. Electrical Symbols

Risk of electric shock

Accuracy: ±(a% of reading + b digits), calibration per year.

Insulation Resistance Measurement

Polarization Index/Dielectric Absorption Ratio Measurement

Low Resistance Measurementc

Open-circuit voltage

Measurement range

Resolution ratio

Accuracy

Approx. 5.0V

0.00~200

0.01Ω

± (2%+3)Ω

Criterion Best

Best

Good

Bad

DAR Value

Criterion

DAR Measurement

PI Measurement

PI Value

10min insulation resistance/1min insulation resistance

Greater than

or equal to 4

4---2

2.0---1.0

Less than or

equal to 1.0

Warning

Greater than

or equal to 1.4

1.25--1.0

Less than or

equal to 1.0

1min insulation resistance/30s insulation resistance

1min insulation resistance/15s insulation resistance

500V

1000V

2500V

Rated voltage

Short circuit current

Accuracy range

Measurement

range

Open circuit

voltage

Rated measurement

current

0.00MΩ ~ 5.00GΩ 0.00MΩ ~ 5.00GΩ 0.00MΩ ~ 20.0GΩ

DC 500V+10%

DC 1000V+10%

DC 2500V+10%

Under 500KΩ

1.00mA~1.10mA

Under 1MΩ

1.00mA~1.10mA

Under 2.5MΩ

1.00mA~1.10mA

Approx. Less than 1.8mA

0.00MΩ~99.9MΩ: ±(3%+5)

100MΩ~10GΩ: ±(5%+5)

10.0GΩ~20.0GΩ: ±(10%+5)

Voltage Measurement

AC voltage

Measurement range

Resolution

Accuracy

30~750V (50/60Hz)

(2%+3)

Low battery indication:

Overload indication: "＞22.0GΩ" shows under insulation

resistance measurement.

display the unit and function simultaneously

● Automatic voltage release

● Backlight for work on dark sites

● Red light for warning

(Altitude: <2000m)

under normal condition)

operating manual, carrying case.

test leads,

● Safety compliances: Overvoltage CATIII 600V, Pollution

Degree 2 as per IEC61010

5. Tester's Structure(Front View)

measurement

for

measurement

7 Switch button for PI/DAR

8 TEST button

9 Rotary knob

LCD Display

6. Buttons and Rotary Knob

1. PI/DAR button: measures polarization index/dielectric absorption

ratio.

2. ZERO/LIGHT button: turns on/off the backlight or resets the

display to zero for low resistance measurement.

3. TEST button: turns on/off insulation and low resistance

measurement.

4. Rotary knob set to ACV: to measure AC voltage.

5. Rotary knob set to CONTINUITY: to measure low resistance.

Need help?

Do you have a question about the UNI-T UT502A and is the answer not in the manual?

Summary

Safety Information and Precautions

General Safety Warnings

Provides critical warnings, dangers, and cautions for safe operation and to prevent damage.

Technical Specifications

Insulation Resistance Measurement Specs

Details rated voltage, measurement range, current, and accuracy for insulation testing.

Polarization Index;Dielectric Absorption Ratio

Specifies criteria and values for PI and DAR measurements.

Low Resistance Measurement Specs

Defines open-circuit voltage, range, resolution, and accuracy for low resistance tests.

AC Voltage Measurement Specs

Details measurement range, resolution, and accuracy for AC voltage.

Testers Front View Components

Component Identification

Identifies key jacks, LCD screen, backlight, and buttons on the tester's front panel.

Controls and Operation

Button Functions

Explains the function of PI/DAR, ZERO/LIGHT, and TEST buttons.

Rotary Knob Functions

Details how to use the rotary knob for ACV, CONTINUITY, and insulation test voltages.

Preparations Before Measurement

Low Battery Indication

Describes the low voltage symbol and the need for battery replacement.

AC Voltage Measurement Procedure

Measurement Steps

Guides on setting the rotary knob, connecting leads, and safety precautions.

Low Resistance Measurement Procedure

Measurement Steps

Outlines wiring, discharge, and test procedure for low resistance.

Insulation Resistance Measurement

Voltage Selection and Procedure

Details selecting test voltage, wiring, and performing continuous measurement.

Polarization Index Measurement

Instructions for measuring PI using the PI/DAR button and TEST button.

Dielectric Absorption Ratio Measurement

Steps for measuring DAR using the PI/DAR button and TEST button.

Battery Replacement Procedure

Replacement Steps

Provides instructions and safety warnings for replacing batteries.

Maintenance

Cleaning and Servicing

Guidelines for cleaning the instrument housing and professional servicing.

Summary

Safety Information and Precautions

General Safety Warnings

Provides critical warnings, dangers, and cautions for safe operation and to prevent damage.

Technical Specifications

Insulation Resistance Measurement Specs

Details rated voltage, measurement range, current, and accuracy for insulation testing.

Polarization Index;Dielectric Absorption Ratio

Specifies criteria and values for PI and DAR measurements.

Low Resistance Measurement Specs

Defines open-circuit voltage, range, resolution, and accuracy for low resistance tests.

AC Voltage Measurement Specs

Details measurement range, resolution, and accuracy for AC voltage.

Testers Front View Components

Component Identification

Identifies key jacks, LCD screen, backlight, and buttons on the tester's front panel.

Controls and Operation

Button Functions

Explains the function of PI/DAR, ZERO/LIGHT, and TEST buttons.

Rotary Knob Functions

Details how to use the rotary knob for ACV, CONTINUITY, and insulation test voltages.

Preparations Before Measurement

Low Battery Indication

Describes the low voltage symbol and the need for battery replacement.

AC Voltage Measurement Procedure

Measurement Steps

Guides on setting the rotary knob, connecting leads, and safety precautions.

Low Resistance Measurement Procedure

Measurement Steps

Outlines wiring, discharge, and test procedure for low resistance.

Insulation Resistance Measurement

Voltage Selection and Procedure

Details selecting test voltage, wiring, and performing continuous measurement.

Polarization Index Measurement

Instructions for measuring PI using the PI/DAR button and TEST button.

Dielectric Absorption Ratio Measurement

Steps for measuring DAR using the PI/DAR button and TEST button.

Battery Replacement Procedure

Replacement Steps

Provides instructions and safety warnings for replacing batteries.

Maintenance

Cleaning and Servicing

Guidelines for cleaning the instrument housing and professional servicing.

Overview

Function Description
Important Technical Specifications
Insulation Resistance Measurement
Polarization Index (PI) / Dielectric Absorption Ratio (DAR) Measurement
Low Resistance Measurement
Voltage Measurement (AC)
General Specifications
Usage Features
Maintenance Features

The UNI-T UT502A is an insulation resistance tester designed for measuring insulation resistance, low resistance, and AC voltage. It features a brand-new design combining massive integrated and digital circuits, offering high accuracy, stable performance, easy operation, and reliability. This instrument is an ideal tool for electric equipment maintenance, testing, and inspection, suitable for insulation materials and various electric equipment like transformers, electric machines, cables, switches, and electrical appliances.

Function Description:

The UT502A primarily measures insulation resistance, low resistance, and AC voltage. It also supports Polarization Index (PI) and Dielectric Absorption Ratio (DAR) measurements, which are crucial for assessing the quality of insulation.

Important Technical Specifications:

Insulation Resistance Measurement:

Rated Voltage: 500V, 1000V, 2500V
Measurement Range:
- 500V: 0.00MΩ ~ 5.00GΩ
- 1000V: 0.00MΩ ~ 5.00GΩ
- 2500V: 0.00MΩ ~ 20.0GΩ
Open Circuit Voltage:
- 500V: DC 500V +10%
- 1000V: DC 1000V +10%
- 2500V: DC 2500V +10%
Rated Measurement Current:
- 500V: 1.00mA ~ 1.10mA (under 500kΩ)
- 1000V: 1.00mA ~ 1.10mA (under 1MΩ)
- 2500V: 1.00mA ~ 1.10mA (under 2.5MΩ)
Short Circuit Current: Approximately less than 1.8mA
Accuracy Range:
- 0.00MΩ ~ 99.9MΩ: ±(3%+5)
- 100MΩ ~ 10GΩ: ±(5%+5)
- 10.0GΩ ~ 20.0GΩ: ±(10%+5)

Polarization Index (PI) / Dielectric Absorption Ratio (DAR) Measurement:

PI Measurement: 10min insulation resistance / 1min insulation resistance
- PI Value > 4: Best
- 4-2: Good
- 2-1: Warning
- < 1: Bad
DAR Measurement:
- 1min insulation resistance / 30s insulation resistance
- 1min insulation resistance / 15s insulation resistance
- DAR Value > 1.4: Best
- 1.25-1.0: Good
- < 1.0: Bad

Low Resistance Measurement:

Open-circuit Voltage: Approximately 5.0V
Measurement Range: 0.00 ~ 200Ω
Resolution Ratio: 0.01Ω
Accuracy: ±(2%+3)Ω

Voltage Measurement (AC):

Measurement Range: 30 ~ 750V (50/60Hz)
Resolution: 1V
Accuracy: ±(2%+3)

General Specifications:

Display: LCD, maximum reading 1999
Low Battery Indication: "[]" symbol
Overload Indication: ">22.0GΩ" for insulation resistance measurement
Automatic Range: Yes
Unit Display: Displays unit and function simultaneously
Automatic Voltage Release: Yes
Backlight: For working in dark sites
Red Light: For warning
Work Condition: 0°C ~ 40°C, relative humidity ≤ 85%
Storage Condition: -20°C ~ 60°C, relative humidity ≤ 90% (Altitude: <2000m)
Dimension: 150mm (L) x 100mm (W) x 71mm (D)
Current Consumption: About 200mA (under maximum 2500V output), about 10mA (under normal condition)
Accessories: Test leads, alkaline battery 1.5V (AA battery) x 6, operating manual, carrying case
Weight: 0.7kg (including battery)
Power: Alkaline battery 1.5V (AA battery) x 6
Safety Compliances: Overvoltage CATIII 600V, Pollution Degree 2 as per IEC61010

Usage Features:

Rotary Knob: Used to select test voltage (500V/1000V/2500V) for insulation resistance, ACV for AC voltage measurement, and CONTINUITY for low resistance measurement.
PI/DAR Button: Initiates Polarization Index and Dielectric Absorption Ratio measurements.
ZERO/LIGHT Button: Toggles backlight and resets the display to zero for low resistance measurement.
TEST Button: Activates/deactivates insulation and low resistance measurements.
Continuous Measurement: The instrument can self-lock to measure continuously after pressing the TEST button, with the test voltage output and the TEST button lighting up. Pressing TEST again unlocks and stops the measurement.
Safety Precautions:
- Always ensure the circuit under test is completely discharged and isolated from the power circuit before measuring resistance.
- Do not measure circuits with voltage over 750VAC.
- Avoid testing in flammable places where sparks could cause explosions.
- Do not operate the instrument if it is wet or if the operator's hand is wet.
- Do not touch conductive parts of test leads during measurement.
- Do not open the battery cover during testing.
- Do not touch the tested line during insulation measurement.
- If the instrument is damaged or has exposed metal, stop using it immediately.
- Exercise extreme caution when working under voltages exceeding 33Vrms, 46.7Vacrms, or 70Vdc, as this can cause electric shock.
- After high resistance measurement, ensure the stored electric charge in the circuit under test is discharged.
Low Battery Indication: The "[]" symbol on the LCD indicates when the battery needs to be replaced.
Automatic Voltage Release: Automatically discharges stored voltage after measurements.

Maintenance Features:

Battery Replacement: When the low battery indicator appears, the 6 x 1.5V AA batteries should be replaced. Ensure the instrument is turned off, test leads are removed, and observe correct polarity during installation. Do not mix old and new batteries.
Cleaning: The instrument housing can be cleaned with a soft cloth or sponge dampened with clean water. Avoid submerging the instrument in water. If it gets wet, dry it before storage.
Repair and Verification: For verification or repair, the instrument should be delivered to a qualified professional serviceman or designated repairing department.
Storage: If the instrument will not be used for a long time, remove the batteries and store it properly. Avoid high temperature, high humidity, inflammable, explosive, or strong electromagnetic field environments.