Brymen BM859s User manual

USER'S
MANUAL
BM857s
BM859s

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1) SAFETY
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 meter protection rating, against the users, is double insulation per
IEC/UL/EN61010-1 Ed. 3.0, IEC/EN61010-2-030 Ed. 1.0, IEC/EN61010-2-033 Ed. 1.0,
IEC/UL/EN61010-031 Ed. 1.1 and CAN/CSA-C22.2 No. 61010-1-12 Ed. 3.0 to
Category III 1000 Volts AC & DC and Category IV 600 Volts AC & DC.
Terminals (to COM) measurement category:
V / A / mAA : Category III 1000 Volts AC & DC, and Category IV 600 Volts AC & DC.
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.
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.

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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
A/mA or A input jack. Only replace the blown fuse with the proper rating as specified
in this manual. Only use the test lead provided with the equipment or UL Listed Probe
Assembly rated CAT III 1000V or better.
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 2006/95/EC and
Electromagnetic compatibility directive 2004/108/EC

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3) PRODUCT DESCRIPTION
Panel Illustration
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
1) 5-4/5 digits 500000
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,
and for T2 (-) function
5) Input Jack (+) for all
functions EXCEPT current
(  A, mA, A) and T2
functions
6) Common (Ground
reference) Input Jack (-)
for all functions EXCEPT
T2 function
7) Input Jack (+) for
milli-amp, micro-amp, and
T2 (+) functions

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sinusoidal waveform, this technique is fast, accurate, and cost effective. In measuring
non-sinusoidal waveforms, however, significant errors can be introduced because of
different scaling factors relating average to RMS values.
AC True RMS
AC True RMS, normally refers as True RMS, identifies a DMM function that is AC
coupled, and responds accurately only to the effective RMS AC component value
regardless of the waveforms. However, DC component plays an important role in the
distorted non-symmetrical waveforms, and will also be of interest sometimes. A full
wave rectified sine waveform is a good example, and the AC true RMS function will
only give the AC component reading which is at 43.6% of the total effective DC+AC
RMS reading.
DC+AC True RMS
DC+AC True RMS calculates both of the AC and DC components given by the
expression when making measurement, and can responds
accurately to the total effective RMS value regardless of the waveform. Distorted
waveforms with the presence of DC components and 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
AC Bandwidth
AC bandwidth of a DMM is the range of frequencies over which AC measurements can
be made within the specified accuracy. It is not the frequency measurement function,
and is the frequency response of the AC functions. A DMM cannot accurately measure
the AC value with frequency spectrums beyond the AC bandwidth of the DMM.
Therefore, wide AC bandwidth plays an important role in high performance DMMs. In
reality, complex waveforms, noise and distorted waveforms contain much higher
frequency spectrum than its fundamental.
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 is a good and
definite ability to reject the effect of AC noise when making DC measurements.