USER GUIDE True RMS Digital Multimeters EX350 Series EX350 True RMS Digital Multimeter EX355 True RMS Digital Multimeter with Temperature
Table of Contents 1. INTRODUCTION 3 2. SAFETY INFORMATION 4 3. DESCRIPTIONS 6 4.
1. Introduction Thank you for selecting the Extech EX350 Series Meter. The EX350 Series are feature‐packed True RMS digital multimeters. In addition to standard DMM features, they offer a Low Impedance (Lo Z) mode, Backlit LCD, Non‐Contact Voltage Detector that safely senses electrical sources, Variable frequency voltage measurement, and Temperature (EX355). This device is shipped fully tested and calibrated and, with proper use, will provide years of reliable service. Please visit our website (www.extech.
2. Safety Information To ensure the safe operation and service of the meter, follow these instructions closely. Failure to observe warnings can result in severe injury. WARNINGS WARNINGS identify hazardous conditions and actions that could cause BODILY HARM or DEATH. When handling test leads or probes, keep hands and fingers behind the finger guards at all times. Remove test leads from the meter before opening the battery compartment or meter housing.
Safety Symbols that are typically marked on meters and instructions This symbol, adjacent to another symbol, indicates the user must refer to the manual or user guide for further information. Risk of electrical shock Fuse symbol Equipment protected by double or reinforced insulation Low Battery symbol Conforms to EU directives Do not discard this product in household trash.
3. Descriptions Meter Description (EX350 pictured) 1. Non‐Contact Voltage Detector and LED 2. LCD multi‐function display 3. Manual Range button 4. Hz% button 5. Mode and LPF Button 6. Rotary function select switch 7. 10A input terminal 8. uA and mA input terminal 9. Common (‐) input terminal 10. Positive input terminal: Voltage, Resistance, Capacitance, Temperature (EX355), and µA 11. Data Hold and backlight button 12. 13.
Display Icon Descriptions Auto: Automatic range mode HOLD: Display hold : Relative mode AC: Alternating Current Measurements DC: Direct Current Measurements : Main display digits A: Amperes (Current) V: Volts (Voltage) o o C/ F: Temperature units F: Farads (Capacitance measurement units) Hz: Hertz (Frequency measurements unit) % Duty Cycle (AC only) Ω (Ohms): Resistance measurement unit LPF Variable frequency voltage mode :Battery status icon ‐ Minus (negative) sign
Push‐Button Descriptions Press the M (MODE) button to perform the following: Switch Position MODE (M) Button Function (EX355) Ω AC DC AC DC AC DC °C °F Ω TEMP (EX355) Press and Hold LPF in the ACV function to select variable frequency tests. Press R (Range) to switch from Auto to Manual Range. Hold to return to Auto Range. Press activates Relative mode. Press to activate Max Min Mode Press to turn HOLD on/off.
4. Operation CAUTION: Read and understand all of the Safety statements listed in the safety section of this manual prior to use. Powering the Meter 1. Turn the rotary function switch to any position to power the meter. Check the batteries if the unit fails to power ON. Refer to the Maintenance section for battery and fuse replacements. 2. Turn the function switch to the OFF position to power OFF the meter. 3.
Voltage Measurements CAUTION: When connecting the test leads to the circuit or device under test, connect the black lead before the red; when removing the test leads, remove the red before the black lead. For safety, be sure to measure a known voltage before using the instrument on an unknown circuit AC Voltage Measurements 1. Insert the black test lead banana plug into the negative (COM) jack and the red test lead banana plug into the positive (V/Ω) jack. 2. Turn the function switch to the 3.
DC Voltage Measurements 1. Insert the black test lead banana plug into the negative (COM) jack and the red test lead banana plug into the positive (V/Ω) jack. 2. Move the Function Switch to the 3. Press the M button to select AC or DC 4. Read the Warning and Caution statements at the beginning of this section to determine whether or not to use the test lead probe covers. 5. Touch the test probe tips to the circuit under test.
10A AC/DC Current Measurements WARNING: Do not handle the test leads above the finger/hand guard barrier. CAUTION: Observe CAT III 600V with respect to Earth Ground. 1. Insert the black test lead into the COM terminal and the red test lead into the A terminal. 2. Turn the meter’s function switch to the display indicating Amperes (Amps). 3. Press the M button to select AC or DC. 4. The meter defaults to the Auto Range mode. When in Auto mode, the display shows the Auto icon.
mA/µA AC/DC Current Measurements WARNING: Do not handle the test leads above the finger/hand guard barrier. CAUTION: Observe CAT III 600V and with respect to Earth Ground. 1. Insert the black test lead into the COM terminal and the red test lead into the mA/µA terminal. 2. Turn the meter’s function switch to the symbol will appear on the display. 3. The meter defaults to the Auto Range mode. When in Auto mode, the display shows the Auto icon. Press the R button to manually range the meter.
Non‐Contact Voltage Detector WARNING: It is possible for voltage to be present in a circuit even if the meter does not beep or flash the NCV LED lamp at the top of the meter. Always verify meter operation on a known live AC current circuit and verify that the batteries are fresh before use. The audible beeper sounds and the LED lamp at the top of the meter flashes when the meter senses an electrical voltage field.
Resistance Measurements Cautions: Switch OFF power to the device under test before measuring. Do not test on circuits or devices where 60VDC or 30VAC is present. 1. Insert the black test lead banana plug into the negative (COM) jack. Insert the red test lead banana plug into the positive (V/Ω) jack. 2. Turn the Function Switch to the Ω position. 3. Use the M button to select the Ω icon on the display indicating resistance only (without the audible continuity icon showing). 4.
Continuity Measurements 1. 2. 3. 4. 5. Insert the black test lead into the negative COM terminal and the red test lead into the positive terminal. Set the function switch to the position. Use the M button to select the Continuity mode. Look for the Continuity icon on the display. Touch the test probe tips across the wire or circuit under test. The continuity threshold is between 10Ω and 100Ω. For measurements below 10Ω the buzzer will always sound.
LoZ AC Voltage Measurements When the function switch is turned to the Lo Z position, the meter applies a low input impedance circuit to the input terminals to eliminate stray or ghost voltages. Refer to the Voltage Measurements section earlier in this guide for Safety information and connection diagrams. 1. Insert the black test lead banana plug into the negative (COM) jack and the red test lead banana plug into the positive (V/Ω) jack. 2. Move the Function Switch to the Lo‐Z position. 3.
Diode Test 1. Insert the black test lead banana plug into the negative COM jack and the red test lead banana plug into the positive jack. 2. Turn the function switch to position. Use the M button to select the diode function if necessary (the diode and voltage symbols will appear on the LCD when in Diode test mode). 3. Touch the test probe tips to the diode or semiconductor junction under test. Note the meter reading. 4. Reverse the test lead polarity by reversing the red and black leads.
Temperature Measurements (EX355 only) 1. Insert the supplied temperature probe into the COM (‐) and positive (+) terminals observing correct polarity. 2. Turn the function switch to the Temp position. Use the M button to select the desired unit of measure. 3. Touch the temperature probe tip to the device under test or leave the temperature probe in the open air to measure ambient temperature. 4. Read the temperature measurement on the LCD. Fig 4‐9 TEMPERATURE MEASUREMENTS 19 EX35x‐en‐GB_V1.
Hz and % Duty Cycle Test Hz and Duty Cycle % are available in the AC Voltage or AC Current functions or can be selected directly in the Hz% position of the function switch. Follow the AC voltage or AC Current procedures for operational details. % Duty Cycle Note: Duty Cycle measurements are AC only for this meter. Measurement signals must be ‘zero crossing’ and must reach ‐0.7V for the meter to properly display Duty Cycle %.
5. Maintenance WARNING: To avoid electrical shock, remove the test leads, disconnect the meter from any circuit and turn OFF the meter before opening the case. Do not operate with an open case. Battery and Fuse Replacement Battery Replacement 1. Remove the test leads from the meter. 2. Remove the meter’s protective cover. 3. Remove the Phillips head screw that secures the battery compartment at the back of the meter.
6. Specifications ELECTRICAL SPECIFICATIONS Accuracy is given as ± (% of reading + least significant digit) at 23C ±5C with relative humidity lower than 80%. Accuracy is specified for a period of one year after calibration. 1. Temperature Coefficient is 0.1 x specified accuracy / C, < 18C (64.5F), > 28C (82.4F) 2. AC Functionality: ACV and ACA specifications are AC coupled, True RMS, 45 to 400Hz; For non‐sinusoidal waveforms, additional accuracy Crest Factor (C.F.
Function DC Current μA mA A Range Resolution EX350 EX355 400.0μA 600.0μA Accuracy 0.1μA 4000μA 6000μA 1μA 40.00mA 60.00mA 10μA 400.0mA 600.0mA 0.1mA 4.000A 6.000A 1mA 10.00A 10.00A 10mA ±(0.7%+2 digits) ±（1.0%+3 digits) Overload protection: μA mA range: (F1) fuse (6.3×32)mm: FF 0.6A H 600V (CE) fast acting 10A range: (F2) fuse (6.3×32)mm: F 10A H 600V (CE) fast acting AC Current Range μA mA A Resolution EX350 EX355 400.0μA 600.0μA Accuracy 0.
Capacitance Range Resolution Accuracy 6.000nF 1pF In REL mode: ± (4%+10 digits) 60.00n F to 600.0μF 10pF to 0.1μF ± (4%+5 digits) 6.000mF to 60.00mF 1μF to 10μF ± 10% Overload protection: 600V‐PTC To optimize accuracy, if the measured capacitance is ≤ 1μF use the REL measurement mode Frequency 9.999Hz to 9.999MHz 0.001Hz to 0.001MHz ± (0.1%+5) Duty Cycle 99.9% 0.1%～ 0.
GENERAL SPECIFCATIONS Display Over‐range indication Conversion rate Maximum Voltage Polarity indication Low battery indication Auto Power OFF EX350 4000 count, EX355 6000 count Multi‐Function LCD “OL” is displayed 2 to 3 updates per second 600VAC RMS or 600V DC maximum applied to any terminal Automatic: positive implied, negative indicated (‐) is displayed.
