Amprobe AM-150-TRMS Operating Manual

USER'S
MANUAL

AM-120 TRMS
AM-130 TRMS
AM-150 TRMS

Digital
Multimeters

1

This manual is applicable to all meter protection versions or otherwise specified

1) SAFETY
Terms in this manual

WARNING identifies conditions and actions that could result in serious injury or even

death to the user.

CAUTION identifies conditions and actions that could cause damage or malfunction in

the instrument.

This manual contains information and warnings that must be followed for operating the
instrument safely and maintaining the instrument in a safe operating condition. If the
instrument is used in a manner not specified by the manufacturer, the protection
provided by the instrument may be impaired. The meter is intended only for indoor use.

The meters (all versions) are protected by double insulation per EN61010-1 and
IEC61010-1 2nd Edition (2001) to CAT III 1000V & CAT IV 600V. The meter (all
versions) also meets CSA C22.2 No. 1010-1-92* to CAT III 1000V.

Standard-version AM-120 & AM-130 Terminals (to COM) ratings:

V : Category III 1000 Volts AC & DC, and Category IV* 600 Volts AC & DC.
A / mAµA : Category III and Category IV* 500 Volts AC and 300 Volts DC.

CF-version AM-150 (Highest-Protection) Terminals (to COM) ratings:

V / A / mAµA: Category III 1000 Volts AC & DC, and Category IV* 600 Volts AC & DC.

*Category IV safety standard (for DMMs) was first released in IEC61010-1 2nd Edition
in year 2001.

Per IEC61010-1 2nd Ed. (2001) Measurement Category
Measurement Category IV (CAT IV) is for measurements performed at the source of

the low-voltage installation. Examples are electricity meters and measurements on
primary overcurrent protection devices and ripple control units.
Measurement Category III (CAT III) is for measurements performed in the building
installation. Examples are measurements on distribution boards, circuit- breakers,
wiring, including cables, bus-bars, junction boxes, switches, socket-outlets in the fixed
installation, and equipment for industrial use and some other equipment, for example,
stationary motors with permanent connection to the fixed installation.

Measurement Category II (CAT II)

is for measurements performed on circuits directly
connected to the low voltage installation. Examples are measurements on household
appliances, portable tools and similar equipment.

2

WARNING
To reduce the risk of fire or electric shock, do not expose this product to rain or
moisture. To avoid electrical shock hazard, observe the proper safety precautions when
working with voltages above 60 VDC or 30 VAC rms. These voltage levels pose a
potential shock hazard to the user. Do not touch test lead tips or the circuit being tested
while power is applied to the circuit being measured. Keep your fingers behind the
finger guards of the test leads during measurement. Inspect test leads, connectors, and
probes for damaged insulation or exposed metal before using the instrument. If any
defects are found, replace them immediately. Do not measure any current that exceeds
the current rating of the protection fuse. Do not attempt a current measurement to any
circuit where the open circuit voltage is above the protection fuse voltage rating.
Suspected open circuit voltage should be checked with voltage functions. Never
attempt a voltage measurement with the test lead inserted into the µA/mA or A input
jack. Only replace the blown fuse with the proper rating as specified in this manual.

CAUTION
Disconnect the test leads from the test points before changing functions. Always set the
instrument to the highest range and work downward for an unknown value when using
manual ranging mode.

INTERNATIONAL ELECTRICAL SYMBOLS

!

Caution ! Refer to the explanation in this Manual

Caution ! Risk of electric shock
Earth (Ground)
Double Insulation or Reinforced insulation

Fuse

AC--Alternating Current

DC--Direct Current

2) CENELEC DIRECTIVES

The instruments conform to CENELEC Low-voltage directive 73/23/EEC and
Electromagnetic compatibility directive 89/336/EEC

3) PRODUCT DESCRIPTION
Panel Illustration

3

1) 3-4/5 digits 5000
counts LCD display

2) Push-buttons for
special functions &
features

3) Selector to turn the
Power On or Off and
Select a function

4) Input Jack for 10A
(20A for 30sec) current
function

5) Input Jack for all
functions EXCEPT
current (µA, mA, A)
functions

6) Common (Ground
reference) Input Jack for
all functions

7) Input Jack for milli­amp and micro-amp
current functions

4

Analog bar-graph

The analog bar graph provides a visual indication of measurement like a traditional
analog meter needle. It is excellent in detecting faulty contacts, identifying
potentiometer clicks, and indicating signal spikes during adjustments.

Average sensing RMS calibrated
RMS (Root-Mean-Square) is the term used to describe the effective or equivalent DC

value of an AC signal. Most digital multimeters use average sensing RMS calibrated
technique to measure RMS values of AC signals. This technique is to obtain the
average value by rectifying and filtering the AC signal. The average value is then scaled
upward (calibrated) to read the RMS value of a sine wave. In measuring pure sinusoidal
waveform, this technique is fast, accurate and cost effective. In measuring non­sinusoidal waveforms, however, significant errors can be introduced because of
different scaling factors relating average to RMS values.

True RMS

True RMS is a term which identifies a DMM that responds accurately to the effective
RMS value regardless of the waveforms such as: square, sawtooth, triangle, pulse
trains, spikes, as well as distorted waveforms with the presence of harmonics.
Harmonics may cause :

1) Overheated transformers, generators and motors to burn out faster than normal

2) Circuit breakers to trip prematurely

3) Fuses to blow

4) Neutrals to overheat due to the triplen harmonics present on the neutral

5) Bus bars and electrical panels to vibrate

Crest Factor

Crest Factor is the ratio of the Crest (instantaneous peak) value to the True RMS value,
and is commonly used to define the dynamic range of a True RMS DMM. A pure
sinusoidal waveform has a Crest Factor of 1.4. A badly distorted sinusoidal waveform
normally has a much higher Crest Factor.

NMRR (Normal Mode Rejection Ratio)
NMRR is the DMM's ability to reject unwanted AC noise effect that can cause
inaccurate DC measurements. NMRR is typically specified in terms of dB (decibel).
This series has a NMRR specification of >60dB at 50 and 60Hz, which means a good
ability to reject the effect of AC noise in DC measurements.

5

CMRR (Common Mode Rejection Ratio)
Common mode voltage is voltage present on both the COM and VOLTAGE input

terminals of a DMM, with respect to ground. CMRR is the DMM's ability to reject
common mode voltage effect that can cause digit rattle or offset in voltage
measurements. This series has a CMRR specifications of >60dB at DC to 60Hz in ACV
function; and >120dB at DC, 50 and 60Hz in DCV function. If neither NMRR nor CMRR
specification is specified, a DMM's performance will be uncertain.

4) OPERATION
DC Voltage, AC Voltage, & Hz Frequency functions

mV function defaults at DC. Press SELECT button momentarily to select AC. Press the

Hz push-button momentarily to
activate or to exit Hz.

Note: Input sensitivity varies automatically with
function range selected before activating the Hz
function. mV function has the highest (300mV) and the 1000V range has the lowest
(300V). It is recommended to first measure the signal voltage (or current) level then
activate the Hz function in that voltage (or current) range to automatically set the most
appropriate trigger level. You can also press the RANGE button momentarily to select
another trigger level manually. If the Hz reading becomes unstable, select lower
sensitivity to avoid electrical noise. If the reading shows zero, select higher sensitivity.

Capacitance, Diode test function

6

Default at

. Press SELECT button momentarily to select Diode test function.

CAUTION

Discharge capacitors before making any measurement. Large value capacitors should
be discharged through an appropriate resistance load.

Normal forward voltage drop (forward biased) for a good silicon diode is between

0.400V to 0.900V. A reading higher than that indicates a leaky diode (defective). A zero
reading indicates a shorted diode (defective). An OL indicates an open diode
(defective). Reverse the test leads connections (reverse biased) across the diode. The
digital display shows OL if the diode is good. Any other readings indicate the diode is
resistive or shorted (defective).

7

Temperature function (AM-130 & AM-150 only)

Press SELECT button momentarily to toggle between °C and °F readings, and the new
setting will be saved automatically in the non-volatile memory as power up default.

Note: Be sure to insert the banana plug K-type temperature bead probe with correct

polarities. You can also use a plug adapter (Optional purchase) with banana pins

to K-type socket to adapt other standard K type mini plug temperature probes.