General GT320 User Manual

WIRELESS DATA LOGGING

MULTIMETER

WITH DOT MATRIX LCD

PLUS NCVD/NCCD

USER’S MANUAL

GT320

Please read this manual carefully and thoroughly before using this product.

(laptop not included)

(includes RD330
Remote Display
with Memory)

TABLE OF CONTENTS

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 –4

Key Features & Specs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

What’s in the Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Safety Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 –8

Product Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 – 11

Setup Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Install Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Insert Test Leads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Operating Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 – 19

General Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Measuring DC or AC Voltage . . . . . . . . . . . . . . . . . . . . . 12 – 13

Measuring Resistance or Capacitance . . . . . . . . . . . . . . . . . 13

Checking the Integrity of a Diode or the . . . . . . . . . . . . . . . . 14

Continuity of a Circuit

Measuring DC or AC Current . . . . . . . . . . . . . . . . . . . . . 14 – 15

Non-Contact AC Voltage/Current Detection (NCVD/NCCD). . . 15

Going Wireless. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 – 19

Transmitting Data to a PC . . . . . . . . . . . . . . . . . 16 – 18

Receiving and Displaying Data from a

Second GT320 or a GT310. . . . . . . . . . . . . . . . . 18 – 19

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 – 22

Maintenance Tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Optional Accessories and Replacement Parts . . . . . . . . . . . . . . . 22

Warranty Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Return for Repair Policy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

2

INTRODUCTION

Thank you for purchasing General Tools & Instruments’ GT320
Wireless Data Logging Multimeter with Dot Matrix LCD plus
NCVD/NCCD. Please read this manual carefully and thoroughly before
using the instrument.

The GT320 can measure—with better than 1% accuracy, in most
cases—the six electrical parameters (DC voltage, AC voltage, DC
current, AC current, resistance and capacitance) that most
professional-grade multimeters measure. Like other multimeters, it
can also be used to verify the integrity of a diode and to check for
continuity within a circuit. However, the GT320 has two safety and
convenience features—NCVD/NCCD and wireless device-to-device
communication—that many comparably priced multimeters lack.

NCVD and NCCD—non-contact voltage and current detection—
empower the electrician in several valuable ways. For example, the
meter’s integrated NCVD sensor can quickly determine which wire in
a group is “live” without the user having to “tap” all the lines. It is so
sensitive it can pinpoint the location of a 30VAC line inside PVC conduit
behind a wooden wall. The NCCD sensor in the GT320 is equally
impressive. It can detect as little as 500 mA of current flowing behind
a concrete or plaster wall, under a floor, above a ceiling, in an
overhead line, or in a buried underground cable. The NCCD sensor can
also detect RF signals (such as from a walkie-talkie) and magnetic
fields.

Wireless communication offers an additional level of safety and
convenience. Being able to read the meter’s measurements from up to
33 ft. (10m) away (on a PC, on a second multimeter in the GT Series,
or on the included RD330 Remote Display with Memory) lets the
electrician observe the effect of throwing a switch or changing a
setting on a piece of equipment without having to be near it. If a
system or piece of equipment operates at high voltages, remote
display makes troubleshooting it safer. If multiple changes to another
system or piece of equipment are needed to troubleshoot a problem,
remote display may save an electrician considerable time by allowing
him or her to immediately see the results of each step taken without
having to shuttle between two areas.

3

The GT320 can be part of three different kinds of wireless
communication schemes.

1. The meter includes a small USB receiver—called a dongle—that
enables any PC to display all the information shown on the unit’s
display. The “Going Wireless” section of this user’s manual provides
instructions for downloading the software needed to activate this
connection. The advantage of using a PC’s monitor to display the
meter’s measurements is readability: readings sent to the screen
of a laptop or desktop computer are several inches high—large
enough to be visible across a room.

2. With two GT320s or one GT320 and one GT310 (essentially, a
GT320 with a dual 7-segment display instead of a dot matrix
display), each meter can be configured to display its own
measurements on its upper readout, and receive and display the
other meter’s measurements on its lower readout. Both models
include the wireless transceiver module needed to “share” readings
remotely—improving safety in the process—in this way.

3. For even greater remote display versatility, use the GT320 with the
included RD330 Remote Display with Memory. The standalone
4 in. x 4 in. unit, which uses the same wireless transceiver module
as the GT320 and GT310, can not only display the readings of two
multimeters simultaneously on its own dual LCD with 0.67 in.
(17mm) high digits; it can also memorize up to 99 readings or pairs
of readings. In addition to its memory, the advantages of using the
RD330 as a remote GT320 display are compactness and portability.

Another key feature of the GT320 is its pair of double-insulated fused
test leads. Like NCVD/NCCD and wireless device-to-device
communication, the fuse in the red test lead offers the electrician
safety and convenience. It not only prevents excessive currents from
flowing through the meter, potentially injuring the user and damaging
the meter. In addition, the position of the fuse makes changing it fast
and easy. In many other multimeters, changing a blown fuse requires
the user to open up the instrument.

The red lead has a unique square plug. The meter's use of a square
(+) jack prevents potentially damaging use of industry-standard round,
non-fused leads.

4

KEY FEATURES & SPECS

• 12 functions, 33 ranges

• Measures AC/DC voltage (up to 750VAC/1000VDC), AC/DC current

(up to 400mA), resistance (up to 40m

Ω) and capacitance (up to

100 uF)

• Verifies integrity of diodes and checks circuits for continuity

• Includes double-insulated test leads; red lead has fast-acting

ceramic fuse rated at 500mA/500V and unique square plug.
Corresponding square jack on meter prevents potentially damaging
use of round, non-fused leads.

• Includes non-contact AC voltage and current detection (NCVD and

NCCD) sensors with beeper

• CAT III 1000V, CAT IV 500V ETL certified

• Wirelessly interfaces to PC at 2.4 GHz from up to 33 ft. (10m) away

via included USB dongle

• Includes transceiver module for wirelessly interfacing to second

GT320 or GT310 (functionally identical model with 7-segment
display) or included RD330 Remote Display with Memory

• Choice of 10 channels for each wireless link

• Flexible, 3-3/4 digit (4000 count), dot matrix LCD with 0.67 in.

(17mm) high digits

• Auto ranging or manual ranging

• Data hold and zero adjust buttons

• Fifteen-minute Auto Power Off function

• Low battery indicator

• Ergonomic design with rugged rubber housing

5

WHAT’S IN THE BOX

The GT320 comes in a black soft pouch with a belt loop inside a box.
Also inside the pouch are:

• A pair of fused test leads (General Part No. TL300)

• A USB dongle (General Part No. GTSF05) for wireless viewing of the

meter’s display on a PC. Software for enabling the dongle to display
the GT310's readings on a PC is downloadable from the GT320 page
of General’s website (www.generaltools.com).

• An RD330 Remote Display with Memory with its own user’s manual

• A “9V” battery

• This user’s manual

SAFETY INSTRUCTIONS

!

WARNING

To avoid possible electric shock or personal injury, and to avoid
damaging the meter or the equipment under test:

• Do not use the meter in any way not detailed in this manual or the

meter’s safety features may be compromised.

• Before using the meter, inspect the case. Do not use the meter if it is

damaged. Look for cracks or missing plastic. Pay particular attention
to the insulation around the connectors.

• !

WARNING

Inspect the test leads for damaged insulation or
exposed metal. Check the test leads for continuity. Replace damaged
test leads before using the meter.

• For safety reasons, you cannot switch to using unfused test leads to
make measurements.

YOU MUST USE FUSED TEST LEADS

fitted with
a fast blow fuse rated at 500mA/500V. Using unfused test leads also
voids the limited warranty.

• Verify the meter’s operation by measuring a known voltage. Do not
use the meter if it operates abnormally. Protection may be impaired.
When in doubt, have the meter serviced.

• !

WARNING

Do not apply more than the rated voltage, as marked on

the meter, between the terminals or between any terminal and ground.

6

• !

WARNING

Do not measure voltages above 600V in CAT III

installations.

• !

WARNING

Do not measure voltage with the rotary dial pointing to
the resistance (ohms), current, capacitance or NCVD or NCCD
positions. Never measure current with the dial pointing to the
resistance (ohms), capacitance or NCVD or NCCD positions.

• Use caution when working with voltages above 42V ACrms, or 60V
DC. These voltages pose a shock hazard.

• Use the proper terminals, function, and range for all measurements.

• !

WARNING

Do not operate the meter around explosive gas, vapor,

or dust.

• !

WARNING

When using the probes, keep your fingers behind the
finger guards. Do not touch the metal probes of the test leads when
making a measurement.

• When making connections, connect the black (–) test lead before
connecting the red (+) test lead; when disconnecting, disconnect the
red (+) test lead before disconnecting the black (–) test lead.

• Disconnect circuit power and discharge all high-voltage capacitors
before measuring/testing resistance, continuity, diodes, or
capacitance.

• For all DC functions in both auto ranging and manual ranging modes,
to avoid the risk of shock due to possible improper reading verify the
presence of any AC voltages by first using the AC voltage
measurement function. Then select a DC voltage range equal to or
greater than the AC range.

• Before measuring current, turn off power to the circuit before
connecting the meter.

• Do not operate the meter with the case (or part of the case)
removed.

• Replace the battery as soon as the low battery indicator “ ”
appears. Operated with a weak battery, the meter might produce
false readings that could lead to electric shock and personal injury.

• Remove the test leads from the meter before opening the meter
case or battery compartment.

7

PRODUCT OVERVIEW

Fig. 1 shows the labels and positions of the controls, indicators and
connectors on the front and top of the GT320. Familiarize yourself with
their functions, as explained below, before moving on to the Setup
Instructions and Operating Instructions.

1. Replaceable 2.4GHz transceiver module (on top of unit)

2. NCCD sensor (on top of unit)

3. NCVD sensor (on top of unit)

4. Dot matrix LCD

5. Backlight

8

GT320

Fig. 1. The
GT320’s controls,
indicators and
connectors