Extech Instruments MG320-NIST User manual

EXCH®
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Insulation Tester+ DMM
Model MG320
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USER MANUAL
Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176
TestEquipmentDepot.com

2 MG320-en-GB_v1.1 1/17
TableofContents
1. INTRODUCTION 3
2. SAFETY 3
3. METERDESCRIPTION 5
4. CONTROLBUTTONS 6
5. SYMBOLSANDANNUNCIATORS 6
6. OPERATINGINSTRUCTIONS 7
6.1DisplayBacklight 7
6.2DataHold 7
6.3LowBatteryIndication 7
6.4DCVOLTAGEMEASUREMENTS 7
6.5ACVOLTAGEMEASUREMENTS 8
6.6LOWRESISTANCE/CONTINUITYMEASUREMENTS 9
6.7INSULATIONRESISTANCEMEASUREMENTS 10
6.7.1DisableInsulationTestLockMode 10
6.7.2InsulationResistanceTestTimeSetup 11
6.7.3DielectricAbsorptionRatio[DAR]InsulationTesting 11
6.7.4PolarizationIndex[PI]InsulationTesting 11
6.7.5ComparatorUtility 12
7. DATARECORDING 12
8. MAINTENANCE 13
8.1BATTERYINSTALLATION 13
8.2REPLACINGTHEFUSE 13
9. SPECIFICATIONS 14

3 MG320-en-GB_v1.1 1/17
1. Introduction
Congratulations on your purchase of the MG320 True RMS Insulation Resistance CAT IV 600V DMM.
The MG320 features a rugged design for heavy duty use. The MG320 measures Insulation
Resistance, AC/DC Voltage, and Resistance.
Insulation Resistance tests are automatic ranging with 5 test voltages from 50V to 1000V. The
MG320 can store and recall up to 99 measurements.
The MG320 is suitable for measuring the insulation resistance on elecrical equipment such as
transformers, motors, cables, switches, and appliances.
Proper use and care of this meter will provide years of reliable service.
Features
True RMS AC/DC Voltage Measurments to 600V
Insulation Resistance Measurements up to 20G
Low Resistance/Continuity Measurements to 20k
Auto Ranging measurements
Polarization Index (PI) and Dielectric Aborption Ratio (DAR) tests
Five (5) Insulation Resistance test voltages (50, 100, 250, 500, and 1000V)
Insulation Resistance tests in10% voltage steps (from 50% to 120% of range)
Front panel LED test voltage alert lamp
Eight (8) Insulation Resistance measurement ranges (automatic ranging)
Pass/Fail Comparator function
Auto-discharge at end of test
High voltage display symbols
Hand’s free test lock feature
Manually store and recall up to 99 readings
Overload indication
Optional remote test probe for controlling the TEST button remotely
Test leads, alligator clips, batteries, user manual, and case included
2. Safety
Warning and Caution safety label
Double Insulation
DC Direct Current
AC Alternating Current
Low Battery
Fuse symbol
High Voltage Alert
Audible beeper
Earth ground
Complies with EC standard

4 MG320-en-GB_v1.1 1/17
PER IEC1010 OVERVOLTAGE INSTALLATION CATEGORY
OVERVOLTAGE CATEGORY I
Equipment of OVERVOLTAGE CATEGORY I is equipment for connection to circuits in which measures are taken
to limit the transient over-voltages to an appropriate low level.
Note – Examples include protected electronic circuits.
OVERVOLTAGE CATEGORY II
Equipment of OVERVOLTAGE CATEGORY II is energy-consuming equipment to be supplied from the fixed
installation.
Note – Examples include household, office, and laboratory appliances.
OVERVOLTAGE CATEGORY III
Equipment of OVERVOLTAGE CATEGORY III is equipment in fixed installations.
Note – Examples include switches in the fixed installation and some equipment for industrial use with permanent
connection to the fixed installation.
OVERVOLTAGE CATEGORY IV
Equipment of OVERVOLTAGE CATEGORY IV is for use at the origin of the installation.
Note – Examples include electricity meters and primary over-current protection equipment
SAFETY INSTRUCTIONS
This meter has been designed for safe use, but must be operated with caution. The rules listed below
must be carefully followed for safe operation.
1. NEVER apply voltage to the meter that exceeds the specified maximum:
Input Protection Limits
Function Maximum Input
V DC or V AC 600VDC/AC rms
Resistance/Continuity 500mA/600V fuse protected input
Insulation Resistance 250VDC/AC rms
Surge Protection: 8kV peak per IEC 61010
2. USE EXTREME CAUTION when working with high voltages.
3. DO NOT measure voltage if the voltage on the "COM" input jack exceeds 600V above earth
ground.
4. NEVER connect the meter leads across a voltage source while the function switch is in the
resistance mode. Doing so can damage the meter.
5. ALWAYS discharge filter capacitors in power supplies and disconnect the power when making
resistance tests.
6. ALWAYS turn off the power and disconnect the test leads before opening the covers to replace
the fuse or batteries.
7. NEVER operate the meter unless the battery/fuse cover is in place and fastened securely.
8. If the equipment is used in a manner not specified by the manufacturer, the protection provided by
the equipment may be impaired.

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Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176
TestEquipmentDepot.com

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

 

 
  
 
 
 

 

 
7. Data Recoing
 
 I) 
 
    

 1i@M) 

1) 
  
Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176
TestEquipmentDepot.com

14 MG320-en-GB_v1.1 1/17
9. Specifications
Function Range Resolution Accuracy
DC Voltage 600V 0.1V (2.0% reading + 3 digits)
AC Voltage 600V 0.1V (2.0% reading + 3 digits)
Specified from 5% of range to 100% of range
Input impedance: 10M
Min. Measured Voltage: 0.1V
Frequency 50~400Hz
Input protection: 600V DC and AC rms
Low Resistance
& Continuity
20.00k0.01(1.5% reading + 3 digits)
Open-circuit voltage is 5.0V approx.
Short-circuit current > 200mA
500mA/600V fuse protected input terminals
Insulation Resistance Measurements
50V test voltage 0.01M~19.99M
20.0M~50.0M
0.01M
0.1M
0.01M~50.0M: (3% + 5 digits)
100V test voltage 0.01M~19.99M
20.0M~100.0M
1M
0.01G
0.01M~100.0M: (3% + 5 digits)
250V test voltage 0.01M~19.99M
20.0M~200.0M
0.01M
0.1M
0.01M~200.0M: (1.5% + 5 digits)
500V test voltage 0.01M~19.99M
20.0M~199.9M
200M~500M
0.01M
0.1M
1Mv
0.01M~500M: (1.5% + 5 digits)
1000V test
voltage
0.01M~19.99M
20.0M~199.9M
200M~2000M
2.0G~20.0G
0.01M
1M
1M
0.1G
0.01M~200.0M: (1.5% + 5 digits)
200M~2000M: (1.5% + 5 digits)
2.0G~10.0G: (10% + 3 digits)
10.0G~20.0G: (20% + 10 digits)
Short-circuit current < 2mA
Insulation Resistance Alerts
50V: 0.01M~50.0M(alert buzzer sounds when resistance is <1M)
100V: 0.01M~100.0M(alert buzzer sounds when resistance is <1M)
250V: 0.01M~200.0M(alert buzzer sounds when resistance is <4M)
500V: 0.01M~500M(alert buzzer sounds when resistance is <4M)
1000V: 0.01M~10.0G(alert buzzer sounds when resistance is <4M)

15 MG320-en-GB_v1.1 1/17
Insulation Resistance Test Voltage Outputs
Output Voltage Test Steps (50~120%) Load Overload Test
current
Short-circuit
current
50V (0%~+10%) 10% steps (25~60V) 50kΩ250VAC/DC 1mA ≤2mA
100V (0%~+10%) 10% steps (50~120V) 100kΩ250VAC/DC 1mA ≤2mA
250V (0%~+10%) 10% steps (125~300V) 250kΩ250VAC/DC 1mA ≤2mA
500V (0%~+10%) 10% steps (250~600V) 500kΩ250VAC/DC 1mA ≤2mA
1000V (0%~+10%) 10% steps (500~1200V) 1MΩ250VAC/DC 1mA ≤2mA
Note: Accuracy is stated at 23oC (75oF) and 45~75% RH.
Note: Calibration interval: 1-year maximum
Note: Temperature coefficient: 0.1 x stated accuracy/C
Note: Accuracy specifications consist of two elements: (% reading) his is the accuracy of the measurement circuit;
(+digits) this is the accuracy of the analog to digital converter.
General Specifications
Display 5999 count, backlit, LCD with bargraph
Ranging Automatic
Storage capacity 99 records (01-99)
Input Impedance >10MΩ
AC Response True rms
ACV Bandwidth 50Hz to 400Hz
Over range indication “>” is displayed
Auto Power Off After 3 minutes of inactivity
Polarity Automatic (no indication for positive); Minus (-) sign for negative
Measurement Rate 2 times per second, nominal
Low Battery Indication “ ” is displayed if battery drops below operating voltage
Battery Six (6) 1.5V ‘AA’ batteries
Consumption 500mA (at a 1000V test voltage); 10mA in nominal conditions
Fuse 500mA/600V fast blow
Enclosure Double molded, IP 40
Operating Temperature 0ºC~40ºC (32ºF~104ºF)
Storage Temperature -20oC~60oC (-4oF~140oF)
Operating Humidity
Storage Humidity
Operating Altitude
Weight
Size
Safety
<85%
<90%
2000m (7000ft.) maximum
0.7kg (1.5 lbs.) with batteries
225[L] x 103[W] x 59[D] mm (8.8[L] x 4.1[W] x 2.3[D] in.)
This instrument is designed in strict compliance with safety standard
IEC61010, overvoltage standard (CAT IV 600V) and pollution degree II.