Amprobe ac68C User manual

AC68C
True RMS AC/DC Clamp Multimeter
Users Manual
PN 2729051
July 2006
©2006 Amprobe®Test Tools.
All rights reserved. Printed in Taiwan
For detailed specifications and ordering info go to www.TestEquipmentDepot.com

AC68C AC/DC TRUE RMS

AC68C
True RMS AC/DC Clamp
Multimeter
Users Manual
English

Limited Warranty and Limitation of Liability
Your Amprobe®product will be free from defects in material and
workmanship for 1 year from the date of purchase. This warranty
does not cover fuses, disposable batteries or damage from
accident, neglect, misuse, alteration, contamination, or abnormal
conditions of operation or handling. Resellers are not authorized
to extend any other warranty on Amprobe®’s behalf. To obtain
service during the warranty period, return the product with proof
of purchase to an authorized Amprobe®Test Tools Service
Center or to a Amprobe®dealer or distributor. See Repair
Section above for details. THIS WARRANTY IS YOUR ONLY
REMEDY. ALL OTHER WARRANTIES - WHETHER EXPRESS,
IMPLIED OR STAUTORY - INCLUDING IMPLIED WARRANTIES
OF FITNESS FOR A PARTICULAR PURPOSE OR
MERCHANTABILITY, ARE HEREBY DISCLAIMED.
MANUFACTURER SHALL NOT BE LIABLE FOR ANY SPECIAL,
INDIRECT, INCIDENTAL OR CONSEQUENTIAL DAMAGES OR
LOSSES, ARISING FROM ANY CAUSE OR THEORY. Since some
states or countries do not allow the exclusion or limitation of an
implied warranty or of incidental or consequential damages, this
limitation of liability may not apply to you.

1
True RMS AC/DC Clamp Multimeter
Contents
Symbols................................................................................. 1
Introduction........................................................................... 1
Warnings and Precautions..................................................... 2
Unpacking and Inspection ..................................................... 2
Instrument Familiarization (See inside front cover)............... 2
Measuring Procedures........................................................... 3
Specifications ........................................................................ 6
Troubleshooting .................................................................... 8
Battery Replacement.............................................................. 9
Repair .................................................................................... 10
Symbols
W Refer to the manual X Dangerous Voltage
T Double insulated
BT
Battery
F Direct Current J Earth Ground
B Alternating Current R Audible tone
P Complies with EU
directives >Underwriters Laboratories, Inc.
Introduction
The AC68C is a true rms digital clampmeter that measures both
AC and DC current as well as AC and DC voltage, Resistance,
Frequency, Continuity and Diode Test.

2
Warnings and Precautions
The AC68C Digital Clampmeter conforms to EN61010-2-032,
EN61010-1, CAT III- 600V, class 2 and pollution deg. 2; and
UL3111-1. It is recommended for use with local level power
distribution, appliances, portable equipment, etc., where only
smaller transient overvoltages may occur, and not for primary
supply lines, overhead lines, and cable systems.
•Do not exceed the maximum overload limits per function
(see specifications) nor the limits marked on the
instrument itself. Never apply more than 600 V dc / ac
rms between the test lead and earth ground.
•Inspect the DMM, test leads and accessories before
every use. Do not use any damaged part.
•Never ground yourself when taking measurements. Do
not touch exposed circuit elements or test probe tips.
•Do not operate the instrument in an explosive
atmosphere.
•Exercise extreme caution when: measuring voltage
>20 V // current >10 mA // AC power line with inductive
loads // AC power line during electrical storms //
current, when the fuse blows in a circuit with open
circuit voltage >600 V // servicing CRT equipment.
•Always measure current in series with the load – NEVER
ACROSS a voltage source. Check fuse first. Never
replace a fuse with one of a different rating.
•Remove test leads before opening the case.
Unpacking and Inspection
Your shipping carton should include:
Digital clamp meter 1
Carrying case 1
Test lead set (one black, one red) 1
One 9V battery (installed) 1
Manual 1
If any of the items are damaged or missing, return the complete
package to the place of purchase for an exchange.
Instrument Familiarization (See inside front cover)
Transformer Jaws: Designed to pick up the current flowing
through the conductor.
Jaw Opening Lever: Press lever to open transformer jaws.
Release pressure to close the jaws.
Digital Display: 3-3/4 digit LCD (max. reading 3999), with
decimal point, AC/DC, polarity, unit and low battery (
BT
)
indicators.
Function/Range Selector: Selects the desired function and range.
Changing position turns instrument back on after Auto-OFF.

3
Peak Hold Button: Toggles on and off. Captures the maximum
peak value of a current or voltage surge (motor start-up). “PEAK”
is shown on LCD.
Data Hold Button: Toggles on and off. Holds reading for all
functions and ranges. Always release HOLD before taking a new
measurement. “HOLD” is shown on LCD.
DCA ZERO Button: Push this button to zero the display before
measuring DC current.
Input Terminals: Always connect black test lead (negative) to
black COM input jack and red test lead to red “VΩ” input jack for
voltage, frequency, resistance, continuity, and diode
measurements
Measuring Procedures
General
1. Make sure that the selected function and range are
suitable for the measurement to be taken.
2. If the measured current is higher than the selected range
for a longer period of time, overheating may occur,
compromising the safety and operation of inner circuits.
3. Do not measure currents on high voltage conductors
(> 600 V) to avoid risks of discharge and/or incorrect
readings.
4. When measuring current, make sure that the test leads are
removed from the meter terminals.
5. The most accurate current reading will be obtained by
placing the conductor in the center of the jaws (aligned
with the centering marks on the transformer jaws).
DC Current Measurement
1. Set the function/range selector to the appropriate A F
position (400 or 600 A).
2. Press the DCA ZERO button to make sure that the display
is zero-reading.
3. Open spring-loaded clamp by pressing the lever on left
side of meter.
4. Position clamp around one wire or conductor and release
the clamp lever. Make sure that the clamp is entirely
closed. The clamp must be positioned around only one
conductor. If it is placed around two or more current
carrying conductors, the reading is FALSE.
5. Read the displayed value. The direction of the current
corresponds to the indication of the pointer on the jaw.
Polarity inversion is indicated by a ’-‘ (minus) symbol on
the display.

4
AC Current Measurement
1. Set the function/range selector to the appropriate A B
position (400 or 600 A).
2. Open spring-loaded clamp by pressing the lever on left
side of meter.
3. Position clamp around one wire or conductor and release
the clamp lever. Make sure that the clamp is entirely
closed. The clamp must be positioned around only one
conductor. If it is placed around two or more current
carrying conductors, the reading is FALSE.
4. Read the displayed value.
DC and AC Voltage Measurement
WWarning
The maximum input voltage for DC or AC Volts is 600 Vrms. Do
not attempt to take any voltage measurement that exceeds
600 Vrms to avoid electrical shock hazard or damage to the
instrument.
1. Set the function/range selector to the appropriate V F
(600 V) or V B(400 or 600 V) position.
2. Connect the black test lead to the “COM” terminal and the
red test lead to the “VΩ’’ terminal. Connect probe tips to
the circuit and read the value.
Frequency Measurement
Note: Both ammeter and voltmeter can be used for frequency
measurement. The clamp-on Ammeter detects the frequency of
the current circulating in the cable or bus-bar under test (the
current must be greater than 1 A in the 400 A range and greater
than 15 A in the 600 A range). The Voltmeter detects the
frequency of the voltage applied to the leads.
1. In either set-up (current or voltage measurement), set the
function/range switch to the Hz position.
2. Read the frequency value on the display.

5
Resistance Measurement
WWarning
Before taking any in-circuit resistance measurement, remove
power from the circuit being tested and discharge all
capacitors.
1. Set the function/range selector to the 4 kΩposition.
2. Connect the black lead to the COM terminal and red lead to
the “VΩ” terminal.
3. Connect the test leads to the resistance or circuit to be
measured and read the value on the display.
Continuity Measurement
WWarning
Before taking any in-circuit continuity measurement, remove
power from the circuit being tested and discharge all
capacitors.
1. Set the function/range selector to the Rposition.
2. Connect the black lead to the COM terminal and red lead to
the “VΩ” terminal.
3. Connect the test leads to the circuit to be tested.
Continuity (resistance ≤40 Ω) is indicated by a continuous
beep tone.
Diode Test
1. Set the function/range selector to the Gposition.
2. Connect the black lead to the COM terminal and red lead to
the “VΩ” terminal.
3. Connect the red test lead to the anode, and the black test
lead to the cathode of the diode to be tested.
4. Read the forward voltage value on the display (approx.
0.6 V for a silicon diode or 0.4 V for a germanium diode).
An open diode is indicated by “OL”.
5. Reverse test lead connections to the diode to perform a
reverse bias test. “OL” indicates a good diode.
Notes: “OL” for both reverse and forward bias tests indicates an
open diode. A low voltage reading for both bias tests indicates a
shorted diode. If the diode is shunted by a resistor of 1000 ohms
or less, it must be removed from the circuit before taking the
measurement. Bipolar transistor junctions may be tested in the
same manner described above as emitter-base and base-
collector junctions are diode junctions.
Peak Hold Measurement
Proceed as for voltage or current measurement (AC or DC).
Before actually taking the measurement, press the PEAK button.
“PEAK” is shown on the display. After taking a measurement, the
displayed reading is the maximum peak value of a surge in the
voltage or current.

6
Data Hold
Proceed as for voltage or current measurement (AC or DC).
While taking a measurement, press the HOLD button. “HOLD” is
shown on the display and the current meter reading is
maintained, even after disconnecting the test leads from the
circuit or removing the conductor from the clamp. Press HOLD
again to deactivate before taking a new measurement.
Specifications
General Specifications
Display: 3-3/4 Digit LCD, max. reading of 3999. Function and
unit indication.
Overrange indication: “OL” indicated.
Polarity indication: automatic; positive implied; negative
indicated.
Zero adjustment: automatic for all functions and ranges except
DC current (Zero adjustment button).
Ranging: manual function and range selection with rotary
selector switch. Autoranging for frequency measurement.
Special functions: Data Hold, Peak Hold
Operating principle: dual slope integration
Sampling rate: 2 /sec, nominal.
Maximum voltage between any terminal and earth ground: 600 V
Low Battery Indication:
BT
when battery voltage drops below
operating voltage.
Auto Power Off: Approx. 30 minutes after no function change.
Environmental Conditions
Operating temperature: 0 °C to +40 °C, <80 % R.H., non-
condensing
Storage temperature: -10 °C to +60 °C, <70 % R.H., battery
removed.
Power source: Single 9 V battery (NEDA 1604,1EC 6F22)
Battery life: Alkaline 200 hours.
Maximum jaw opening: 40 mm (1.57 inches)
Pollution degree: Level II
Altitude: < 2000 meters
Size (WxLxH): 76x228x39 mm (3”x9”x1.5”)
Weight: 465 gr (incl. battery)
Accessories: Test leads, battery, manual and carrying case.