Sinometer BM3548, BM3549 User Manual

User Manual of BM3548 and BM3549

Insulation Tester and Multimeter

Distinguished users:

Thank you for purchasing the meter of our company. To use the meter
correctly, please read the operating instructions thoroughly and carefully before
use it, especially the section of “Safety information”.
Please keep the operating instructions in a safe place after reading it, putting it
where the meter is or keeping it in handy for future reference.

Attention: A test cable is provided for the meter. It is not allowed to

perform insulation test by holding the test cable with your hands. Ensure
that the to-be-tested object is securely clamped and keep your body away
from the circuit before press the TEST key to output high voltage.

I. Overview

Welcome to use the product!

BM3548/49 digital multimeter with auto range selection is a real digital
insulating resistance tester + digital millimeter. It has features of complete
functions, high accuracy, reliability in operation, and convenience in use. Output
test voltage can be switched among 250V/500V/1000V/2500V, depending on
different models. An ordinary insulating resistance meter can not measure the
output high voltage of its own. When the output high voltage of the insulating
resistance meter doesn’t conform to the rated value, it is not easy for the user to
find the unconformity so that deviation of the measured result is over large
sometimes and causing hidden troubles in safety. BM3548/49 can monitor the
output high voltage in a real-time way. At any time, the user can observe actual
measurement voltage that is output by the meter, effectively avoiding
misjudgment caused due to output voltage not conforming to the rated value.
The measurement range of the meter can reach up to 40GΩ. The measurement
time can be set up according to requirements. After a measurement is completed,
the measured result can be kept automatically. Functions of the digital
multimeter include AC/DC voltage, current, resistance, capacitance, frequency,
diode, and ON/OFF measurement. The functions of the digital multimeter are
completely separated from those of the insulating resistance tester. When use
functions of the multimeter, you need not be worried that you would suffer
electric shock due to high voltage generated by the insulating resistance tester.
The product is applicable to measurement of the insulating resistance of various
insulating materials and electric equipments such as transformers, motors,
cables, switches, and electric apparatuses. It is also applicable to maintenance,
test, and inspection of various electric equipments. It is compact in structure,
convenient to carry, and an ideal electrical and electronic testing meter of yours.

II. Safety information

(1) Description of safety marks:

Warning: important safety information the user must read！

Danger: high-voltage electric shock is present！

Double-insulated protection

(2) Read the operating instructions carefully before use the meter.
(3) It is strictly prohibited to use the meter before its rear cover is put in place.

Otherwise, it might cause an electric shock.

(4) Check and make sure the insulating layer of the test cable is in good

condition without any breakage.
(5) To avoid electric shock, do not touch the test cable and the circuit under test

when performing a test.

1

(6) Make sure one end of the test cable is securely inserted into the terminal.
(7) During test, any range must not exceed its specified maximum input value.
(8) During test, do not operate the switch knob for changing a range to avoid
damaging the meter.

(9) DC voltage over 50V or AC voltage over 36V can cause danger of electric
shock. Be careful when taking measurement.

(10) Before performing insulation test, make sure the range selection switch has

been set within an appropriate voltage range.

(11) Do not perform insulating resistance test in a combustible environment.

Spark may cause explosion.

(12) Stop using the meter, if its case or test cable is broken during use and the

metal is exposed

(13) When open the rear cover for changing battery, make sure the test cable has

been removed out of the test terminal and the range switch switched to

OFF position.
(14) Take the battery out when the meter will not be used for a long time.
(15) When “

- +

” is displayed in the meter, it is necessary to change the battery

in time to ensure measurement accuracy.

III. Name and function of parts (see the figure)

1． Function switch knob

Switch among power ON/OFF, measurement voltage of the insulating
resistance, and various functions of the multimeter.
2．TEST/STOP key: it is used to measure the insulating resistance
RANGE key: it is used to switch between hand-operated and auto range mode
as the meter is used as the multimeter. The function is not available when the
meter is used as the insulating resistance tester. On startup, the meter is preset
to auto range mode. Press the key to switch to hand-operated range mode. In
hand-operated range mode, every time press the key, the range goes up one
level until to the maximum level. After the maximum level is reached, every
time press the key, the range goes to the minimum level. The process is
repeated. If press and hold the key over 2 seconds, the meter is switched to
auto range mode.
3．SELECT key: it is used to set the measurement time of the insulating
resistance as well as various function switch of the same position

4．DH/BL key

Data hold/backlight function: press the key to lock the displayed result.
Press it again to restore normal measurement (when OL is displayed in the
meter, Hold function is not available). Press and hold the key for 2 seconds to
switch between backlight on/off (in adjustment mode, backlight is not
available).
5．L (LIN E) input terminal (connected to line terminal of the to-be-tested

object).

6．V/Ω/mA/Hz/CAP input terminal: common positive input terminal of the
digital multimeter;
7．COM/G input terminal (COM is common EARTH of the multimeter /G is
shielded terminal of the insulating resistance).
8．E (EARTH) input terminal (connected to EARTH terminal of the
to-be-tested object)
9．Liquid crystal display

Small 8888: measured value of high voltage
of the insulating resistance

-8888: measured value of various functions
Min: measurement time of the insulating

resistance (minute)
OL: overflow display, indicating the measured
value exceeds the maximum display value.
ERR: indicating that serious current leakage
or short circuit occurs to the equipment

- +

: Battery capacity is insufficient
10 Indicator light of high voltage
11 Holding box of the test cables

12 Ring used to fasten the hanging strip
IV. General characteristics

(1) Auto range: “OL” will be displayed for overload.
(2) Display mode: Liquid crystal display; maximum display: 4000；
(3) Sampling rate: 2 times per second；
(4) The meter can display actual insulation test voltage. LED light is used to
indicate high voltage output status；
(5) Operating environment: 0°C-40°C, less than 75%RH；
(6) Storage environment:-10°C-60°C, less then 80%RH；
(7) Maximum power consumption: 4.5W; minimum power consumption 18mW.
(8) Indication for insufficient battery capacity: “

- +

” is displayed；

(9) Power supply: 6 pieces of AA 1.5V battery (LR6×6)
(10) Auto power off: The multimeter is turned off automatically in approx. 15

minutes after it is turned on if no key is pressed or the knob is not turned.

(11) External dimension: 170(length)×156(width)×64(height)mm

(12) Weight: Approx. 650 grams (including the battery)

V. Technical characteristics and operating description of the insulation
tester

Accuracy:±% reading ± number, one-year warranty
Environment to guarantee the accuracy: 23°C±5°C, less than 75%RH

Rated measurement voltage, valid measurement range, and precision

Rated voltage Measurement range Accur acy
250V 0.25M-400MΩ
500V 0.5MΩ-4GΩ
1000V 1.5M-40G
2500V 5M-40GΩ

0.2M-200MΩ:±3%rdg±5,
200M-4GΩ:±5%rdg±5,
4G-40GΩ:±10%rdg±5

2

Display range

Rated voltage Display range (auto range ) Resolution
250V 4M/40M/400MΩ 1k/10K/100KΩ
500V 4M/40M/400M/4GΩ 1k/10K/100K /1MΩ
1000V 40M/400M/4G/40G 10k/100K/1M /10MΩ
2500V 40M/400M/4G/40GΩ 10k/100K/1M /10MΩ

Characteristics of the measurement terminal

Rated

voltage

Allowed range

of open circuit

voltage

The measurement resistance value that

can maintain lower limit of the rated

voltage

short circuit

current

250V 250KΩ (ERR is displayed when it is

less than 200KΩ)

500V 500KΩ (ERR is displayed when it is

less than 400KΩ)

1000V 1.5MΩ (ERR is displayed when it is

less than 1MΩ)

2500V

90%-110% of the

rated voltage

5MΩ (ERR is displayed when it is less

than 2MΩ)

Not less than

1.5mA

Usage for insulating resistance measurement

Danger: If there is any measurement error, it may cause personal injury
and meter failure. Operate it only after read the operating instructions carefully
and thoroughly. Our company will take no responsibility for the accident not
caused due to any reason of our company.

Operating description

1. Safety information

1) Watch out for high-voltage electric shock. When completing the

insulating resistance test, remove the test cable only after making sure high
voltage across the tested object is less than 50V.

2) During measurement, do not touch the object under test and watch out for
high-voltage electric shock.

3) When test the insulating resistance, the object should not be electrified.
Make sure the to-be-tested object is securely earthed. Before test, it is necessary
to short-circuit and discharge two test terminals of the to-be-tested object.

4) When test the insulating resistance, make sure no external voltage is
applied to the test circuit.

5) Before starting test, make sure position of the range switch knob is correct
and the test cable is securely connected.

6) After press the high voltage key, high voltage from 250V to 2500V will
be output between L terminal and E terminal (depending on different models
and positions). Here, be sure not to touch the meter and exposed part of the
object under test. Otherwise, danger of electric shock would occur.

2． Insulating resistance test

1) Connection of the test terminals

Insert one end of the test pen with a high voltage test bar into L terminal
socket of the meter. Insert one end of the test cable with a test clamp into E
terminal socket of the meter. Insert one end of the test cable with a black test
pen (the pen with a clamp) G terminal socket of the meter. Make a good
connection respectively.

2) Test connecting cable
Connecting cable of E terminal socket of the meter is earthing cable；
Connecting cable of L terminal socket of the meter (with a high voltage test bar)

is circuit cable；
Connecting cable of G terminal socket of the meter (the pen with a clamp) is
shielding cable and connected to surface of the to-be-tested object to prevent
surface leakage and affect impedance test.

3) Rated voltage selection

Select a rated voltage you need in the insulating resistance test. Turn the range

switch knob to a corresponding voltage position, and press “SELECT” to
make selection among 1min/2min/10min according to test time requirement

4) Connect pen of the test bar to another terminal of the to-be-tested object.

Press high voltage switch (TEST/STOP). Here, the red indicator light turns
on, indicating high voltage output for test is connected. Actual high voltage
value can be displayed in the meter.

After the test is started, numerical value is displayed in the meter. The

displayed value is the insulating resistance value of the object under test. For
convenience of use, when the set test time comes, the meter cuts high voltage
off automatically, and locks and saves the measured result. When the
measured result is less than the set minimum resistance value under the
measurement voltage, “ERR” is displayed in the meter. If there is a need to
remeasure, press any key to release the lock status and start the measurement
over again.

Attention: do not short-circuit the two test pens with high voltage output or take

measurement of insulating resistance after high voltage is output. The
improper operation is very easy to generate spark, cause fire disaster, and
damage the meter.

Special attention in operation:
Before test, make sure the to-be-tested circuit is not electrified. Do not take
measurement of any electrified equipment or electrified circuit. During test,
dangerous voltage output exists in the meter. Be sure to operate it carefully.
Ensure the to-be-tested object is securely clamped and keep your hands away
from the test clamp before press TEST key to output high voltage.
Attention in operation:
When use 500V measurement voltage to measure resistance less than 2MΩ,
1000V to measure resistance less than 5MΩ, and 2500V to measure resistance
less than 10MΩ, measurement time must not exceed 10 seconds.

5) Power off
After the test is completed, release lock status of the meter and observe
voltage display value of the insulating resistance tester. When it is less than 50V,
turn the range switch knob to OFF position, and then remove the test cable. The
test is over.

Attention: the meter can not be turned off automatically when it is used as

an insulating resistance tester. Please turn the range switch knob to OFF
position after the test is over.

Notices in use of the insulating resistance tester

1. Brief introduction

The insulating resistance tester can be used to verify completeness of motor,
transformer, switching equipment, and coil and cable of electric equipment. For
example, when electric cable or switching equipment (low capacitance
equipment) is tested, time-related capacitive leakage current is not noticeable
and would quickly drop to zero. Within a short time (one minute or less), it will
reach a stable conductive leakage current quantity of, providing a good
condition for spot-check of reading/short-time impedance test.
In the other hand, time-related current will last for several hours when the
equipment under test is long cable, large-sized motor or generator (high
capacitance equipment). The current would cause ceaseless change of the
reading of the insulating resistance tester. It is impossible to obtain an accurate
reading. If trend analysis among readings can be made, for example, step
voltage or medium absorption test, the situation can be overcome. The analysis
doesn’t rely on a single reading, but on a large quantity of related readings. As
time-related current drops quickly when low capacitance equipment is tested,
results from multiply tests are the same. Therefore, use of the multiply test
method will waste time.

2, Test in assembly

The most important reason of the insulation test is to ensure the public and

individual safety. Through high voltage DC test among live wire, earthing and
earthing wire, you can eliminate short circuit or earthing phenomenon that is
dangerous to the human life. Usually, the test is performed after preliminary
equipment installation is completed. Performing the test can find connection
error and defective equipment, guarantee high quality installation, and prevent
fire disaster or explosion.

3. Test in maintenance

Another important reason of the insulation test is to protect and lengthen
service life of electric system and motor. Electric system is affected by such
factors as dust, grease, temperature, stress, and vibration for a long time. These
conditions may cause insulating deterioration, loss in production, and even fire
disaster. Regular maintenance and test can provide very valuable information
of system wear and tear status and help forecast system failure possibility.
Solving problems in time can guarantee that a system operates without any
fault and effectively lengthen service life of various equipments.

To obtain meaningful insulating resistance result, an electrician should check

the to-be-tested system carefully before take measurement. When the following
conditions are satisfied, the best results will be obtained:

1) Shut down the system or equipment and disconnect it from other circuits,
electric switches, capacitors, electric brushes, lightning rods, and circuit
breakers. Ensure the test is not affected by leakage current that flows through
switches and over-current protection components.

2) The temperature should be higher than dew point of the environmental air. If
the condition is not satisfied, a layer of water smoke will be formed in the
insulating surface. In some cases, it would be absorbed by insulating material.

3) In surface of the conductor there should be no carbon and other impurity that

are easy to form a conductor.

4) The applied voltage should not be too high. When low voltage system is
tested, too high voltage would cause overload or damage a insulator.

5) The to-be-tested system should be fully discharged to the earth. The earthing
discharge time should be approx. fivefold of the charge time.

6) Temperature influence is worth attention. As insulating resistance is in

inverse ratio with insulating material temperature (the higher the temperature is,
the lower the impedance is). The recorded impedance reading would be changed
by insulating material temperature. It is suggested to perform measurement in a
standard temperature of 20℃ (68

o

F). Compare a reading with a result at a

temperature of 20℃ according to conventional practice. with a temperature over
20℃, the impedance value at 20℃ will be twofold of its reading every time the
temperature goes up for 10℃ (18

o

F); with a temperature under 20℃, the

impedance value at 20℃ will be one half of its reading every time the