Tenmars TM-87, TM-88 User Manual
Autoranging True RMS Multimeter
TM-87 / TM-88
User’s manual
HB2TM8700000
TM-87/TM-88
Contents:
1. SAFETY PRECAUTIONS AND PROCEDURES..........................................................2
1.1. Preliminary ............................................................................................................2
1.2. During use.............................................................................................................3
1.3. After use................................................................................................................3
1.4. Measuring (overvoltage) categories definitions .....................................................3
2. GENERAL DESCRIPTION...........................................................................................4
2.1. Mean value and TRMS: definition..........................................................................4
2.2. True root mean square value and crest factor: definition.......................................4
3. PREPARATION FOR USE...........................................................................................5
3.1. Initial......................................................................................................................5
3.2. Supply voltage.......................................................................................................5
3.3. Calibration .............................................................................................................5
3.4. Storage..................................................................................................................5
4. OPERATING INSTRUCTIONS.....................................................................................6
4.1. Instrument - description.........................................................................................6
4.1.1. Front panel................................................................................................................... 6
4.2. Description of function keys...................................................................................7
4.2.1. HOLD key..................................................................................................................... 7
4.2.2. PK/REL key..................................................................................................................7
4.2.3. MX/MN key................................................................................................................... 7
4.2.4. R/SEL key.................................................................................................................... 7
4.2.5. Backlight key ( )...................................................................................................... 8
4.2.6. Disable Auto Power OFF .............................................................................................8
4.3. Measurements.......................................................................................................9
4.3.1. DC Voltage measurement............................................................................................ 9
4.3.2. AC Voltage measurement.......................................................................................... 10
4.3.3. DC Current measurement.......................................................................................... 11
4.3.4. AC Current measurement.......................................................................................... 12
4.3.5. Resistance measurement and Continuity Test ..........................................................13
4.3.6. Diode test................................................................................................................... 14
4.3.7. Capacitance measurement........................................................................................ 15
4.3.8. Frequency measurement........................................................................................... 16
4.3.9. Temperature test (Only for TM-88) ............................................................................17
5. MAINTENANCE .........................................................................................................18
5.1. General information.............................................................................................18
5.2. Battery replacement ............................................................................................18
5.3. Fuse replacement................................................................................................19
5.4. Cleaning ..............................................................................................................19
5.5. End of life ............................................................................................................19
6. TECHNICAL SPECIFICATIONS ................................................................................20
6.1. Technical features...............................................................................................20
6.1.1. Electrical specifications.............................................................................................. 22
6.1.2. Safety......................................................................................................................... 22
6.1.3. General data .............................................................................................................. 23
6.2. Environment ........................................................................................................23
6.2.1. Environmental conditions........................................................................................... 23
6.2.2. EMC and LVD............................................................................................................ 23
6.3. Accessories.........................................................................................................23
6.3.1. Standard accessories................................................................................................. 23
7. SERVICE....................................................................................................................24
7.1. Warranty conditions.............................................................................................24
7.2. After-sale service.................................................................................................24
1
TM-87/TM-88
1. SAFETY PRECAUTIONS AND PROCEDURES
This meter is in compliance with safety Standards EN 61010-1 related to electronic
measuring instruments. For your own safety and to avoid damaging the instrument follow
the procedures described in this instruction manual and read carefully all notes preceded
by this symbol
.When taking measurements:
• Avoid doing that in humid or wet places - make sure that humidity is within the limits
indicated in paragraph 6.2.1.
• Avoid doing that in rooms where explosive gas, combustible gas, steam or excessive
dust is present.
• Keep you insulated from the object under test.
• Do not touch exposed metal parts such as test lead ends, sockets, fixing objects,
circuits etc.
• Avoid doing that if you notice anomalous conditions such as breakages, deformations,
fractures, leakages of battery liquid, blind display etc.
• Be particularly careful when measuring voltages exceeding 20V to avoid risk of
electrical shocks.
The following symbols are used:
CAUTION - refer to the instruction manual - an improper use may damage the
instrument or its components
Danger high voltage: risk of electric shocks
Double insulated meter
AC voltage or current
DC voltage or current
1.1. PRELIMINARY
• This instrument has been designed for use in environments of pollution degree 2.
• It can be used for VOLTAGE and CURRENT measurements on installations of overvoltage
CAT III 1000V and CAT IV 600V.
• This instrument is not suitable for measurements of non sine wave voltage and current.
• When using the instrument always respect the usual safety regulations aimed at
protecting you against the dangerous electric currents and protecting the instrument
against incorrect operations.
• Only the leads supplied with the instrument guarantee compliance with the safety
standards in force. They must be in good conditions and, if necessary, replaced with
identical ones.
• Do not test or connect to any circuit exceeding the specified overload protection.
• Do not effect measurements under environmental conditions exceeding the limits
indicated in paragraphs 6.1.1 and 6.2.1.
• Make sure that batteries are properly installed.
• Before connecting the test probes to the installation make sure that the rotary selector
is positioned on the right function.
• Make sure that LCD and rotary selector indicate the same function.
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TM-87/TM-88
1.2. DURING USE
CAUTION
An improper use may damage the instrument and/or its components or
injure the operator.
• When changing the range, first disconnect the test leads from the circuit under test in
order to avoid any accident.
• When the instrument is connected to measuring circuits never touch any unused
terminal.
• When measuring resistors do not add any voltage. Although there is a protection
circuit, excessive voltage could cause malfunctioning.
• If during measurement the displayed values remain constant check whether the HOLD
function is active.
1.3. AFTER USE
• After using the instrument turn it off.
• If you expect not to use the instrument for a long period remove the battery to avoid
leakages of battery liquids which may damage its inner components.
1.4. MEASURING (OVERVOLTAGE) CATEGORIES DEFINITIONS
EN 61010-1: Safety requirements for electrical equipment for measurement, control and
laboratory use, Part 1: General requirements, gives a definition of measuring category,
usually called overvoltage category. Paragraph 6.7.4: Measuring circuits:
(OMISSIS)
circuits are divided into the following measurement categories:
• Measurement category 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 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 fixed installation.
• Measurement category 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..
• Measurement category I is for measurements performed on circuits not directly
connected to MAINS.
Examples are measurements on circuits not derived from MAINS, and specially
protected (internal) MAINS-derived circuits. In the latter case, transient stresses are
variable; for that reason, the norm requires that the transient withstand capability of
the equipment is made known to the user.
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TM-87/TM-88
2. GENERAL DESCRIPTION
This meter performs the below listed measurements:
• DC and AC TRMS Voltage
• DC and AC TRMS Current
• Resistance and Continuity test
• Frequency
• Capacitance
• Diode test
All selectable by means of a 10 position rotary selector (including OFF position). Functions
keys are also available (see chapter 4.2). An analogical bargraph is also available. The
selected quantity is displayed with indication of measuring unit and active functions.
The instrument disposes of an Auto Power Off function consisting in an automatic
switching off 30 minutes after last selector rotation or function selection.
2.1. MEAN VALUE AND TRMS: DEFINITION
Safety testers for AC quantities are divided in two big families:
• MEAN VALUE instruments, measuring only the value of the wave at the
fundamental frequency (50 or 60 Hz)
• TRUE ROOT MEAN SQUARE (or “TRMS”) instruments, measuring the true root
mean square value of the quantity under test.
In presence of a perfectly sinusoidal wave, both families provide identical results. While in
presence of distorted waves, readings are different. Mean value instruments provide only
the value of the fundamental wave while TRMS instruments provide the value of the entire
wave, including harmonics (within the passband of the instrument). Accordingly, if the
same quantity is measured with both kinds of instruments, the measured values are
identical only if the wave is purely sinusoidal. Should it be distorted, TRMS instruments
provide higher values than MEAN VALUE instruments.
2.2. TRUE ROOT MEAN SQUARE VALUE AND CREST FACTOR: DEFINITION
The effective current value is defined as follows: “In an interval of time equivalent to a
period, an alternate current with effective value having an intensity of 1A, by passing on a
resistor, disperses the same energy which would be dispersed in the same period of time
by a direct current having an intensity of 1A”. From this definition comes the numerical
expression: G=
∫
+Tt
t
dttg
T
0
0
)(
1
2
The effective value is indicated as RMS (root mean square).
The Crest Factor is defined as the ratio between the Peak Value of a signal and its
effective value: CF (G)=
RMS
p
G
G
. This value varies according to the waveform of the signal,
for a purely sinusoidal wave it’s worth
2 =1.41. In presence of distortions the Crest Factor
assumes higher values as long as the wave distortion is higher.
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TM-87/TM-88
3. PREPARATION FOR USE
3.1. INITIAL
This instrument was checked both mechanically and electrically prior to shipment. All
possible cares and precautions were taken to let you receive the instrument in perfect
conditions. Notwithstanding we suggest you to check it rapidly (eventual damages may
have occurred during transport – if so please contact the local distributor from whom you
bought the item).
Make sure that all standard accessories mentioned in paragraph 6.3.1 are included.
Should you have to return back the instrument for any reason please follow the
instructions mentioned in paragraph 7.
3.2. SUPPLY VOLTAGE
The instrument is supplied by 1x9V battery type NEDA1604 JIS006P IEC6F22. When
battery is low, a low battery indication “
” is displayed. To replace/insert battery please
refer to paragraph 5.2.
3.3. CALIBRATION
The instrument complies with the technical specifications contained in this manual and such
compliance is guaranteed for 1 year. Annual recalibration is recommended.
3.4. STORAGE
After a period of storage under extreme environmental conditions exceeding the limits
mentioned in paragraph 6.2.1 let the instrument resume normal measuring conditions
before using it.
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TM-87/TM-88
4. OPERATING INSTRUCTIONS
4.1. INSTRUMENT - DESCRIPTION
4.1.1. Front panel
LEGEND:
1. LCD
2. HOLD Key
3. PK/ REL Key
4. MX/ MN Key
5. R/SEL Key
6. Backlight
Key
7. OFF position
8. DCV position
9. ACV position
10. Posizione Ω/
11.
position
12.
position
13. Hz position
14. µADC position
℃ and ℉ position(TM-88)
15. µAAC position
DCµA and ACµA position(TM-88)
16. DCA and ACA position
17. COM,A,and VΩ
Hz µA
℃ ℉
Fig. 1: Instrument description
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TM-87/TM-88
4.2. DESCRIPTION OF FUNCTION KEYS
When pressing a key, the corresponding symbol is displayed with a beep. To resume
default state turn the selector on another function.
4.2.1. HOLD key
By pressing HOLD key the measured value is frozen on the display where the symbol
"HOLD" appears. Press again HOLD to disable this function and resume normal operation.
4.2.2. PK/REL key
This key have the double function of measuring max/min peak values (active for ∼V and
∼µA positions of rotary selector) and performing relative measurements (REL) for
V, A,
Hz, Ω/
, , and µA positions of rotary selector.
This key have the double function of measuring max/min peak values (active for ∼V and
∼µA positions of rotary selector) and performing relative measurements (REL) for
V, Hz,
Ω/
, , and ℃/℉ positions of rotary selector.(TM-88)
Press cyclically PK/REL to measure and save peak values. “P
MAX” and “PMIN” symbols on
the display correspond to Maximum Peak and Minimum Peak values respectively which
are continuously updated by the meter. By keeping pressed PK/REL key for at least 3
seconds, “CAL” symbol appears on the display and the meter performs an auto calibration
permitting a higher accuracy on peak measurements.
To exit this function keep pressed PK/REL for at least one second or rotate the selector on
another position.
By pressing PK/REL key, the relative measurement is activated: the meter saves the
(offset) value on the display and the “REL” symbol is shown. The following measurement
will be referred to this offset value. By pressing again PK/REL key the offset value is
shown and the “REL” symbol is blinking.
To exit this function keep pressed PK/REL for at least one second or rotate the selector on
another position.
4.2.3. MX/MN key
By pressing MX/MN key, maximum and minimum values are measured. Both values are
stored and automatically updated as soon as an higher value (MAX) or lower value (MIN)
are measured by meter. The symbol corresponding to the desired function is displayed:
“MAX” for maximum value, “MIN” for minimum value. MX/MN key is disabled when HOLD
function is active.
To exit this function keep MX/MN key pressed for at least 1 second or rotate the selector
to another position.
4.2.4. R/SEL key
By pressing R/SEL key the manual selection of measured range (exception
, ∼A and
A positions) and the selection of a double function which are included on selector (by
choosing between Ω measure and AC or DC Current) are possible. The “MANU”
symbol is shown at display by pressing R/SEL key and the cyclically pressure of the key
change the measuring range and fix the decimal point on the display. Press R/SEL key at
least 1second or rotate the selector to exit from this function and restore the “AUTO”
symbol at display.
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TM-87/TM-88
4.2.5. Backlight key ( )
By pressing key it’s possible to activate the backlight function on the display. The
function automatically disabled itself after some seconds and is available on each position
of the rotary selector.
4.2.6. Disable Auto Power OFF
When the meter is to be used for long periods of time, the operator might want to disable
the AutoPowerOFF function. Once the AutoPowerOFF function is disabled the meter stays
on continuously. To disable the AutoPowerOFF function:
• Switch OFF the meter.
• Turn ON the meter keeping pressed PK/REL, MX/MIN and R/SEL keys.
The AutoPowerOFF function is automatically activated when turning ON again the meter.
8
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