HT21 Compact Digital Multimeters in CAT III User Manual

User manual
Copyright HT ITALIA 2017
Release EN 2.00 – 01/09/2017
HT21

SAFETY PRECAUTIONS AND PROCEDURES

This meter is in compliance with safety standard IEC/EN61010-1 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
• 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 risks of electrical shocks

The following symbols are used:
CAUTION – Refer to the instruction manual – an improper use may damage the instrument or its components
Double insulated instrument
AC Voltage
DC Voltage
Ground reference
1.1. PRELIMINARY INSTRUCTIONS

• This instrument has been designed for use in environments of pollution degree 2

• It can be used for VOLTAGE measurements on installations of CAT III 600V

• This instrument can perform only AC sinusoidal voltage measurements

• You must comply with the usual safety regulations aimed at protecting you against the
  dangerous electric current and protecting the instrument against an incorrect operation

• Only the original test leads supplied along with the instrument guarantee compliance with the safety standards in force.

• They must be in a good condition and, if necessary, replaced with identical ones

• Do not test nor connect to any circuit exceeding the specified overload protection

• Do not take measurements under environmental conditions exceeding the limits indicated in § 7.2.1

• Make sure that the battery is correctly 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

1.2. DURING USE
Read the recommendations which follow and the instructions in this manual:
CAUTION
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, the excessive voltage could cause malfunctioning
• If during the 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
IEC/EN61010-1 guideline: 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. § 6.7.4: Measuring circuits:
(OMISSIONS)
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 a 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

GENERAL DESCRIPTION

The instrument performs, in completely Auto range, the below measurements:

• DC Voltage
• AC Voltage
• Resistance and Continuity test
• Capacitance
• Frequency
• Duty cycle
• Diode test

All selectable by means of a 5 position rotary selector (including OFF position). Also are available the HOLD key to hold the displayed value and enable/disable the backlight feature, the Hz% key for manual selection of frequency and duty cycle measurements, the REL key for Relative measures, and the MODE key for selection of different features which are common to the same position of the rotary selector. The selected quantity is displayed with an 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 the last selector rotation.

PREPARATION FOR USE

3.1. INITIAL CHECKS
This instrument was checked both mechanically and electrically prior to shipment. All possible care and precautions were taken to let you receive the instrument in perfect condition. 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 § 7.3.1 are included. Should you have to return back the instrument for any reason please follow the instructions mentioned in § 8.
3.2. SUPPLY VOLTAGE
The instrument is supplied by a 1x9V battery type IEC 1604 NEDA 6F22. When the battery is low, a ” ” low battery indication is displayed. To replace/insert the battery please refer to § 6.2.
3.3. STORAGE
After a period of storage in extreme environmental conditions exceeding the limits mentioned in § 7.2.1 let the instrument resume normal measuring conditions before using it.

NOMENCLATURE

4.1. INSTRUMENT DESCRIPTION

CAPTION:

1. LCD display
2. MODE key
3. REL key
4. Hz% key
5. HOLD key
6. Function selector
7. COM input jack
8. VΩHz%  input jack

4.2. DESCRIPTION OF FUNCTION KEYS
4.2.1. HOLD key By pressing the HOLD key the measured value is frozen on the display where the symbol “HOLD” appears. Pressing again HOLD to disable this function and resume normal operation. By pressing the key at least 1 second the enable/disable of the backlight feature can be performed. This feature is active for any position of rotary selector.
4.2.2. Hz% key
By pressing the Hz% key the selection of frequency and duty cycle measurements on Hz% and Hz% positions of a selector is performed. The frequency range is different in these two positions.
4.2.3. REL key By pressing REL the relative measure is activated. The meter sets the display to zero and saves the actual value as a reference. The “REL” symbol is shown on display. This function is not active on Hz, Duty Cycle, Continuity Test, and Diode Test measurements. Pressing again the key to exit from this function.
4.2.4. MODE key
By pressing the MODE key the selection of double measured functions which are present at display is performed. In particular this key is active only in position to select among Diode Test, Continuity Test, and Resistance measurements.
4.2.5. Auto Power OFF
The instrument automatically turns off 30 minutes after last pressure of keys or last selector rotation. To resume operation turn the selector on OFF and turn on the instrument again.

OPERATING INSTRUCTIONS

5.1. DC VOLTAGE MEASUREMENT
CAUTION
The maximum input for DC voltage is 600V. Do not attempt to measure higher voltages to avoid electrical shocks or damage to the instrument.

Fig. 2: Using the meter for DC Voltage measurement

1. Switch on the “DC” symbol is displayed
2. Insert the test leads into the jacks, the red plug into VHz% ****jack, and the black plug into the COM jack
3. Connecting the red and black test leads to the positive and negative poles of the circuit under test respectively (see Fig. 2). The voltage value is displayed
4. If the message “O.L” is displayed the higher range is reached
5. The symbol “-” on the instrument display indicates that voltage has an opposite direction with regard to the connection of Fig. 2
6. For HOLD function and Relative measurement please refer to § 4.2

5.2. AC VOLTAGE MEASUREMENT
CAUTION
The maximum input for AC voltage is 600V. Do not attempt to measure higher voltages to avoid electrical shocks or damage to the instrument.
Fig. 3: Using the instrument for AC Voltage measurement

1. Switch onȲ Hz%. “AC” symbol is displayed
2. Insert the test leads into the jacks, the red plug into VHz% **** jack, and the black plug into the COM jack
3. Connect the test leads to the circuit under test (see Fig. 3). The voltage value is displayed
4. If the message “O.L” is displayed the higher range is reached
5. Pressing the Hz% key until the symbols “Hz” or “%” are shown at the display to mean the readings of frequency or duty cycle associated with voltage AC value
6. For HOLD function and Relative measurement please refer to § 4.2

5.3. RESISTANCE AND CONTINUITY TEST MEASUREMENTS
CAUTION
Before taking resistance measurements in-circuit remove power from the circuit being tested and discharge all capacitors.
Fig. 4: Using the instrument for Resistance and Continuity test measurements

1. Switch on . “ ****” symbol is displayed
2. Insert the test leads into the jacks, the red plug into VHz% ****jack, and the black plug into the COM jack
3. Connect the test leads to the circuit under test (see Fig. 4). The resistance value is displayed
4. If the message “O.L” is displayed the higher range is reached
5. Press the MODE key until the symbol is shown at the display to mean the Continuity test and connect the meter as resistance measurement. Buzzer emits a sound if the measured resistance value is less about R<35
6.  For the HOLD function please refer to § 4.2

5.4. DIODE TEST
CAUTION
Before taking diode test measurements in-circuit remove power from the circuit being tested and discharge all capacitors.
Fig. 5: Using the instrument for the Diode test

1. Switch on Ω ****
2. Pressing the MODE key until the symbol is shown at the display to mean the diode test
3. Insert the test leads into the jacks, the red plug into VHz% ****jack, and the black plug into COM jack
4. Connect the test leads to the diode under test observing the proper polarities indicated in Fig.5. The threshold voltage value expressed in mV under this situation is displayed
5. If the threshold voltage value is 0V the diode P-N junction is shorted circuit
6. If the message “O.L” is displayed the diode terminals are reversed, the diode P-N junction is damaged

5.5. FREQUENCY AND DUTY CYCLE MEASUREMENTS
CAUTION
The maximum input for AC voltage is 250V. Do not attempt to measure higher voltages to avoid electrical shocks or damages to the instrument.
Fig. 6: Using the instrument for Frequency and Duty cycle measurements

1. Switch on Hz%. “Hz” symbol is displayed
2. Insert the test leads into the jacks, the red plug into VHz% jack, and the black plug intoV ΩHZ% ****jack
3. Connect the test leads to the circuit under test (see Fig. 6). The frequency value, with kHz or MHz units, is displayed
4. If the message “O.L” is displayed the higher range is reached
5. Press the Hz% key until the “%” symbol is shown at the display to mean the Duty Cycle test and connect the meter as frequency measurement. The measured value is displayed
6. For the HOLD function please refer to § 4.2

5.6. CAPACITANCE MEASUREMENT
CAUTION
Before taking capacitance measurement in the circuit remove power from the circuit being tested and discharge all capacitors. Connect the test capacitor to the inputs respecting the polarity connections when required.
Fig. 7: Using the instrument for Capacitance measurement

1. Switch on ****
2. Pressing the MODE key until the “nF” symbol is shown at the display to mean the capacitance measurement
3. Insert the test leads into the jacks, the red plug into VHz% jack, and the black plug into VHZ% jack
4. Press the REL key before starting the measurement
5. Connect the red and black test clamps to the capacitor terminals respecting if necessary the proper polarities (see Fig. 7). The capacitance value is shown on display
6. If the message “O.L” is displayed the higher range is reached
7. For HOLD function and Relative measurement please refer to § 4.2

MAINTENANCE

6.1. GENERAL INFORMATION

• In order to go guarantee the performance of the instrument be sure to use it according to these instructions and keep it stored in suitable environmental conditions
• Do not expose it to high temperatures or humidity or direct sunlight
• Be sure to turn it off after use. If you expect not to use the instrument for a long period remove batteries to avoid leakages of battery liquid which could damage its inner components.

6.2. BATTERY REPLACEMENT
When the ” ” low battery indication is displayed the battery is to be replaced.
CAUTION
Before replacing the battery disconnect test leads from any energized circuits to avoid electrical shocks.

1. Turn OFF the instrument
2. Disconnect the test leads from the input terminals
3. Remove the fixing screws from the back case and detach it
4. Replace the battery with a new one of the same type (refer to § 7.1.2) observing the proper polarities
5. Replace the back case and screws
6. Use the appropriate battery disposal methods for your area

6.3. CLEANING
To clean the instrument use a soft dry cloth. Never use a wet cloth, solvents, or water.
6.4. END OF LIFE
CAUTION: This symbol indicates that equipment, the battery, and its accessories shall be subject to a separate collection and correct disposal.

TECHNICAL SPECIFICATIONS

7.1. TECHNICAL FEATURES
Accuracy calculated as [%reading + (num. dgts*resolution)] at 18°C28°C, <70%RH

DC Voltage (Auto range)

Range

| Resolution| Accuracy| Input impedance|

Overload protection

---|---|---|---|---
4.000V| 0.001V| ****

±(1.2%rdg+2dgt)

| ****

7.8MW

| ****

600VDC/ACrms

40.00V| 0.01V
400.0V| 0.1V
600V| 1V| ±(1.5%rdg+2dgt)

AC Voltage (Auto range)

Range

| Resolution| Accuracy (50 ¸ 400Hz)| Input impedance|

Overload protection

---|---|---|---|---
4.000V| 0.001V| ±(1.2%rdg+4dgt)| 7.8MW| **** 600VDC/ACrms
40.00V| 0.01V| ±(1.5%rdg+3dgt)
400.0V| 0.1V
600V| 1V| ±(2.0%rdg+4dgt)

Resistance (Auto range)

Diode Test

Feature| Resolution| Accuracy| Max open voltage| Overload protection
---|---|---|---|---
****| 1mV| ±(10%rdg + 5dgt)| circa 1.5VDC| 250VDC/ACrms

Continuity test

Frequency (Auto range)

Range| Resolution| Accuracy| Sensitivity| Overload protection
---|---|---|---|---
5.000Hz| 0.001Hz| ±(1.5%rdg + 5dgt)| >8Vrms| 250VDC/ACrms
50.00Hz| 0.01Hz
500.0Hz| 0.1Hz| ±(1.2%rdg + 3dgt)
5.000kHz| 1Hz
50.00kHz| 10Hz
500.0kHz| 100Hz
5.000MHz| 1kHz| ±(1.5%rdg + 4dgt)
10.00MHz| 10kHz

Duty cycle (Autorange)

Range| Resolution| Accuracy| Sensibilità| Overload protection
---|---|---|---|---
0.5 – 99%| 0.1%| ±(1.2%rdg + 2dgt)| >8Vrms| 250VDC/ACrms

Capacitance (Autorange)

7.1.1. Reference guidelines

7.1.2. General data
Mechanical characteristics

7.2. ENVIRONMENT
7.2.1. Environmental conditions

This instrument satisfies the requirements of Low Voltage Directive 2014/35/EU (LVD) and of EMC Directive 2014/30/EU
This instrument satisfies the requirements of European Directive 2011/65/EU (RoHS) and 2012/19/EU (WEEE)

ACCESSORIES

7.3.1. Accessories provided

1. Pair of test leads
2. Battery
3. Carrying bag
4. User manual

SERVICE

8.1. WARRANTY CONDITIONS
This instrument is guaranteed against material or production defects, in accordance with our general sales conditions. During the warranty period, the manufacturer reserves the right to decide either to repair or replace the product. Should you need for any reason to return back the instrument for repair or replacement take prior agreements with the local distributor from whom you bought it. Do not forget to enclose a report describing the reasons for returning (detected fault). Use only original packaging. Any damage that occurred in transit due to nonoriginal packaging will be charged anyhow to the customer. The manufacturer will not be responsible for any damage to persons or things.
The warranty doesn’t apply to:

• Accessories and batteries (not covered by warranty)
• Repairs made necessary by improper use (including adaptation to particular applications not foreseen in the instructions manual) or improper combination with incompatible accessories or equipment
• Repairs made necessary by improper shipping material causing damages in transit
• Repairs made necessary by previous attempts for the repair carried out by nonskilled or unauthorized personnel
• Instruments for whatever reason modified by the customer himself without the explicit authorization of our Technical Dept
• Faults due to adaptation to a particular application not provided for by the definition of the equipment or by the instruction manual
• The contents of this manual may not be reproduced in any form whatsoever without the manufacturer’s authorization.

Our products are patented and our logotypes are registered. We reserve the right to modify specifications and prices in view of technological improvements or developments which might be necessary.
8.2. AFTER-SALE SERVICE
Shouldn’t the instrument work properly, before contacting your distributor make sure that batteries are correctly installed and working, check the test leads, and replace them if necessary? Make sure that your operating procedure corresponds to the one described in this manual. Should you need for any reason to return back the instrument for repair or replacement take prior agreements with the local distributor from whom you bought it. Do not forget to enclose a report describing the reasons for returning (detected fault). Use only original packaging. Any damage that occurred in transit due to nonoriginal packaging will be charged anyhow to the customer. The manufacturer will not be responsible for any damage to persons or things.

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