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HT Instruments PQA924 User Manual
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HT Instruments PQA924 User Manual

HT Instruments PQA924 User Manual

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© Copyright HT ITALIA 2025
Release EN 1.00 - 21/03/2025

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Summary of Contents for HT Instruments PQA924

  • Page 1 © Copyright HT ITALIA 2025 Release EN 1.00 - 21/03/2025...
  • Page 2 PQA924 TABLE OF CONTENTS PRECAUTIONS AND SAFETY MEASURES ............3 1.1. General information ......................3 1.2. Preliminary instructions ....................... 4 1.3. During use ........................... 5 1.4. After use ..........................5 GENERAL DESCRIPTION ..................6 2.1. Foreword ..........................6 2.2. Instrument functions ......................6 2.3.
  • Page 3 PQA924 8.1. General information ......................64 8.2. Replacing or recharging internal batteries ................. 64 8.3. Instrument cleaning ......................65 TECHNICAL SPECIFICATIONS................66 9.1. Technical specifications ..................... 66 9.2. General characteristics ...................... 70 9.3. Environmental conditions for use ..................71 9.4. Accessories ........................71 APPENDIX –...
  • Page 4 PQA924 1. PRECAUTIONS AND SAFETY MEASURES 1.1. GENERAL INFORMATION This instrument has been designed to comply with the IEC/EN61010-1 Directive on electronic measuring equipment. For your safety and to avoid damage to the instrument, please follow the procedures described in this manual and read carefully all instructions...
  • Page 5 PQA924 1.2. PRELIMINARY INSTRUCTIONS • The instrument has been designed to be used in the environmental conditions specified in § 9.3. The presence of significantly different environmental conditions can compromise the safety of the instrument and the operator. In any case, before using the instrument, wait until the conditions inside the instrument are comparable to the environment in which it will be used.
  • Page 6 PQA924 1.3. DURING USE Read the following recommendations and instructions carefully: CAUTION Failure to comply with the Warnings and/or Instructions may result in damage to the instrument and/or its components or personal injury to the operator. • When the instrument is connected to the circuit under consideration, never touch any unused terminal.
  • Page 7 2.2. INSTRUMENT FUNCTIONS PQA924 is able to capture any critical event related to the quality of electrical energy: fast voltage transients, harmonics and interharmonics of voltage and current, power harmonics, voltage drops, Flicker analysis, i.e. all the possible parameters that allow to characterise the electrical system in question.
  • Page 8 PQA924 3. PREPARATION FOR USE 3.1. INITIAL CHECKS The instrument has been electrically and mechanically checked. All possible precautions have been taken so that it could be delivered without damage. However, it is advisable to check it briefly to see if it has been damaged during transport. If anomalies are found, contact your freight forwarder immediately.
  • Page 9 PQA924 4. DESCRIPTION OF PARTS 4.1. INSTRUMENT DESCRIPTION CAPTION: 1. Inputs for voltages and currents 2. TFT display with "touchscreen" 3. F1, F2, F3, F4 function keys 4. ,, , arrow keys and ENTER 5. GO/STOP key 6. ESC/MENU key 7.
  • Page 10 PQA924 4.2. DESCRIPTION OF FUNCTION KEYS The description of the function keys on the instrument is given below. Function key Description Press ON/OFF key and release it after approx 1s to turn on the instrument. To turn off the instrument keep the key pressed for ON/OFF approx 2s.
  • Page 11 PQA924 4.3. DISPLAY DESCRIPTION The display is a 73x57mm (320x240pxl) colour TFT graphic module with resistive "touch- screen" technology, which allows direct interaction using the PT400 pen pointer supplied, inserted into the side of the instrument, or with the fingers (the use of gloves does not affect operation).
  • Page 12 PQA924 5. GENERAL MENU Each time the instrument is switched on, it automatically displays the "General Menu" screen shown in Fig. 6 below, where the icons can be selected directly by touch or by using the arrow and ENTER keys. A blue frame always surrounds the selected icon.
  • Page 13 PQA924 5.1. GENERAL INSTRUMENT SETTINGS Fig. 7: General Menu Screen – General Settings Section In this section you can set the following parameters: ➢ System Language ➢ System Date/Time ➢ Display brightness ➢ Password protection for recordings. ➢ Sound associated with the keys.
  • Page 14 PQA924 5.1.2. Definition of measuring cable colors and internal parameters The instrument allows the “color” customization of the connection cables (voltages and current transducers) by mounting the supplied colored rings on them, as shown in Fig. 9 CAPTION: 1. Termination of the test cable for voltage measurement 2.
  • Page 15 PQA924 5.1.3. Adjusting the display brightness 1. Open the drop-down menu " " corresponding to the field "Brightness (%)" 2. Set the percentage value of the brightness in the field: 0% ÷ 100% 3. Press SAVE or the "OK" virtual key, or the F4 function key to save the selected setting which will be retained even after the instrument is switched off 4.
  • Page 16 PQA924 5.1.7. Setting the WiFi Hotspot The instrument can manage a connection with a PC to download data stored in the memory via a WiFi connection, which can be activated in this section. 1. Move the virtual selector of the "WiFi Hotspot" field to "On" to activate or "Off" to deactivate the function 2.
  • Page 17 PQA924 5.1.9. Setting the operator's name This option allows entering the name of the operator who performs the measurements with the instrument. This name will be included in the reports created using the management software. 1. Touch the corresponding field in the "Operator" section. The following screen will be displayed Fig.
  • Page 18 PQA924 6. Move the virtual format selector to the "24h" position (24 hour format) or to the "AM/PM" position by touching it 7. Press SAVE or the "OK" virtual key, or the F4 function key to save the selected setting which will be retained even after the instrument is switched off 8.
  • Page 19 PQA924 Fig. 15: Setting the IP Address in the HTagorà Software – DHCP Mode Static IP Mode 10. To manually define the LAN network connection parameters, select the "User defined" option in the IP field, as shown in Fig. 16: Setting the communication via Ethernet network – Def. by user Mode CAUTION •...
  • Page 20 PQA924 Fig. 17: Setting Ethernet network parameters – User defined Mode 12. Use the virtual keyboard to set the IP address value and confirm the operation by touching the " " symbol 13. Touch the value associated with the "Gateway" field. The screen in Fig. 17 – right side is shown on the display 14.
  • Page 21 PQA924 5.2. ANALYSER CONFIGURATION Fig. 19: Analyser Configuration In this section, the instrument allows making basic and advanced selections in relation to the type of system being tested and the transducers used. In particular, it is possible to select/set: ➢ The type of system, rated voltage and frequency ➢...
  • Page 22 PQA924 2. Touch the figure on the screen to change the type of electrical system to be tested. The instrument cyclically shows the following options: ➢ Single-phase 2 Wires system (see § 6.1.1) ➢ 3-Phase 4 Wires system (see § 6.1.2) ➢...
  • Page 23 PQA924 ➢ Rigid clamp standard clamp-on → transducer with rigid toroid (see models in the packing list attached to the instrument) connectable via ACON3F5M adapter ➢ HTFlex315 → flexible clamp-on transducer for AC current up to 6000A, max inner diameter of the toroid 50mm ➢...
  • Page 24 PQA924 CAUTION Always leave the default value "1" if there are no VTs in the system to obtain a correct direct measurement of the voltage 7. Press the SAVE key or the "OK" virtual key, or the F4 function key to save the selected settings that remain even after the instrument is switched off 8.
  • Page 25 PQA924 6. Open the drop-down menu " " corresponding to the "Phase Current Clamp FS [A]" field by selecting the FS of the clamp-on transducer with rigid toroid inserted in the secondary circuit of the CT from the options: 1A, 5A, 10A 7.
  • Page 26 PQA924 CAUTION Always leave the default value "1" if there are no VTs in the system to obtain a correct direct measurement of the voltage 13. Press the SAVE key or the "OK" virtual key, or the F4 function key to save the selected settings that remain even after the instrument is switched off 14.
  • Page 27 PQA924 5.3. RECORDER CONFIGURATION Fig. 27: Recorder configuration In this section, the instrument allows defining the following operations: ➢ Insertion of any comments on the recording that will be present in the print report ➢ Setting of the main aggregation interval (time frame between two consecutive saves of the main network parameters within the measuring process) ➢...
  • Page 28 PQA924 5.3.1. Setting the recording parameters 1. Select the "Recording Config." mode. The instrument will show the screen in Fig. 28 – left part Fig. 28: Recording unit settings screen 2. Touch the "Settings" menu to access the screens for setting the recording parameters 3.
  • Page 29 PQA924 11. Touch and move the virtual selector of the "Recording Start" field to one of the following positions: ➢ Man. → Manual start of recording with the GO/STOP key at the next "00" instant after the key is pressed ➢...
  • Page 30 PQA924 20. Touch and move the "Harmonics" field virtual selector to "On" (activation of harmonic analysis recording) or to "Off" (deactivation of harmonic analysis recording). The following screen will appear: Fig. 31: Activation/deactivation of harmonic analysis parameters recording 21. The following parameters can be selected: ➢...
  • Page 31 PQA924 CAUTION The Min and Max values are expressed in % of the Vnom value of § 5.2.1 24. Touch and move the virtual selector of the "Fast Transient" field (see § 10.6) to "On" (activation of fast voltage transients recording with minimum resolution 1µs) or to "Off"...
  • Page 32 PQA924 31. Open the drop-down menu " " in the "Time [s]" field to set time detection interval of the event within the range: 0.2s ÷ 10.0s in steps of 0.2s 32. Touch and move the virtual selector in the "Flicker" field (recording of the Flicker phenomenon on the input voltages of the instrument in relation to the requirements of the IEC/EN 61000-4-15 standard - see §...
  • Page 33 PQA924 5.4. MULTIMETER FUNCTION Fig. 36: Multimeter Function In this section, the instrument displays the values of the measurements made in real time on the input channels and calculated internally with regard to voltages, AC TRMS currents, the set of electrical parameters for each phase and totals, Flicker values, voltage unbalance,...
  • Page 34 PQA924 PARAMETER KEY P1, P2, P3 → Active power on phases L1, L2, L3 PT → Total system active power Q1, Q2, Q3 → Reactive power on phases L1, L2, L3 QT → Total system reactive power S1, S2, S3 → Apparent power on phases L1, L2, L3 ST →...
  • Page 35 PQA924 PARAMETER KEY: V3N →Phase L3 - Neutral voltage THDV3N → Voltage total harmonic distortion V3N PkV3N →Voltage peak value V3N VNPE →N-PE voltage I3 → Phase I3 current THDI3 → Current total harmonic distortion I3 Freq → Voltage frequency P3/Q3/S3 →...
  • Page 36 PQA924 PARAMETER KEY: Ea1,Ea2,Ea3→ Active energy produced L1,L2,L3 EaT → Total active energy produced Eri1,Eri2,Eri3 → Inductive reactive energy produced L1,L2,L3 EriT → Total inductive reactive energy produced Erc1,Erc2,Erc3 → Capacitive reactive energy producedL1,L2,L3 ErcT → Total capacitive reactive energy produced PkD1 →...
  • Page 37 PQA924 5.1.2. Signal waveform display The following is a sample screen for a three-phase four-wire system with country = Europe. Similar considerations apply to any other recording system and country selected. The number of screens available depends on the type of system considered.
  • Page 38 PQA924 CAUTION • Touch points on the waveform to move the fuchsia cursor to the desired points by reading the value in Fig. 46 – part 9 . Use the  and  arrow keys to move the cursor along the time axis in 0.1ms increments •...
  • Page 39 PQA924 5. When the 4 currents are selected, the waveforms of the individual phases and the neutral are shown in the following figure Fig. 49: Display of current waveforms 6. When the voltages and currents of the individual phases are selected, the...
  • Page 40 PQA924 5.1.3. Display of harmonic analysis In the presence of a page relating to numerical values , it is possible at any time to select the display of the tables and bar graphs of the harmonic analysis of voltages, currents and powers by pressing the F3 key or by touching the "Harmonic"...
  • Page 41 PQA924 1. Touch the "Setting"button (see Fig. 52 – part 4). The following screen appears on the display: Fig. 53: Select the display setting of the harmonics graphs 2. The following selections are described below: ➢ Harmonics → display of harmonics V and I or Power ➢...
  • Page 42 PQA924 6. When the 4 voltages are selected the bar graphs of the individual voltages V1N, V2N, V3N and VNPE are shown in Fig. 55 - left part Fig. 55: Harmonic analysis of voltages in numerical format with graph 7. The screen displays the amplitudes of the selected harmonics in "%" or "RMS" format and the percentage values of the "THD"...
  • Page 43 PQA924 14. When the voltage and current signals of each phase are selected, the bar graphs of the pairs V1N&I1, V2N&I2, V3N&I3 or VNPE&IN are shown in Fig. 57 Fig. 57: Harmonic analysis of voltage and current for each phase 15.
  • Page 44 PQA924 Fig. 59: Harmonic analysis of the active powers 22. The screen displays the graphs of the harmonic amplitudes of the active powers absorbed (positive value) or produced (negative value) selected in "%" or "W" format, with different measurement scales for each quantity. Use the vertical/horizontal Zoom tools and the translation bars in order to view the desired values 23.
  • Page 45 PQA924 5.1.4. Vectorial diagram display In the presence of a page relating to numerical values, it is possible to select at any time the display of the vector diagram of voltages and currents by pressing the F4 key or by touching the "Vectors"...
  • Page 46 PQA924 5. The following parameters are shown: ➢ |V1N|, |V2N|, |V3N| → Module amplitudes values of the fundamentals of the voltages V1N, V2N, V3N and VNPE ➢ V1N - V2N → phase shift between V1N phasor and V2N phasor ➢ V2N - V3N → phase shift between V2N and V3N phasor ➢...
  • Page 47 PQA924 CAUTION • Vector analysis refers to the polar coordinates (amplitude and phase) of the fundamental harmonics (h=01) of voltages and currents • The voltage vectors are normalised on the outermost circle that is touched by the maximum module of the signal •...
  • Page 48 PQA924 6. OPERATING INSTRUCTIONS 6.1. INSTRUMENT CONNECTIONS TO THE SYSTEM The following connection diagram are applicable when Europe is selected on the instrument. The figures refer to the accessories supplied with the KIT802 kit. Refer to Table 1 for ring colours to be inserted on cables associated with other countries.
  • Page 49 PQA924 6.1.2. Three-Phase 4 Wires system CAUTION The maximum voltage between inputs L1, L2, L3, N and E is 1000V AC CAT IV 600V to earth. Do not measure voltages that exceed the limits indicated in this manual. Exceeding the voltage limits may result in electric shock to the user and damage to the instrument.
  • Page 50 PQA924 6.1.3. Three-Phases 3 Wires system CAUTION The maximum voltage between inputs L1, L2, L3 and E is 1000V AC CAT IV 600V to earth. Do not measure voltages that exceed the limits indicated in this manual. Exceeding the voltage limits may result in electric shock to the user and damage to the instrument.
  • Page 51 PQA924 6.1.4. Three-Phase 3 Wires Aron system CAUTION The maximum voltage between inputs L1, L2, L3 and E is 1000V AC CAT IV 600V to earth. Do not measure voltages that exceed the limits indicated in this manual. Exceeding the voltage limits may result in electric shock to the user and damage to the instrument.
  • Page 52 PQA924 6.1.5. Three-Phase 4 Wires system and 3P HL central socket CAUTION The maximum voltage between inputs L1, L2, L3, N and E is 1000V AC CAT IV 600V to earth. Do not measure voltages that exceed the limits indicated in this manual.
  • Page 53 PQA924 6.1.6. Three-Phase 3 Wires system 3P 2E CAUTION The maximum voltage between inputs L1, L2, L3, N and E is 1000V AC CAT IV 600V to earth. Do not measure voltages that exceed the limits indicated in this manual. Exceeding the voltage limits may result in electric shock to the user and damage to the instrument.
  • Page 54 PQA924 6.1.7. Split Phase 3 Wires 1P PC system CAUTION The maximum voltage between inputs L1, L2, L3, N and E is 1000V AC CAT IV 600V to earth. Do not measure voltages that exceed the limits indicated in this manual. Exceeding the voltage limits may result in electric shock to the user and damage to the instrument.
  • Page 55 PQA924 6.2. AUTOSET FUNCTION It is recommended to use the Autoset mode to avoid possible gross connection errors, with the consequent presence of inconsistent values for some electrical quantities, which could lead to the need to repeat the recording. The most common connection errors are those related to the interchanging of clamps on the conductors, resulting in phase differences between the voltage and current signals.
  • Page 56 PQA924 5. Touch "OK" to confirm. → The function is executed and after a few moments the screen in Fig. 71 – right side is displayed if the Autoset is correct. The following parameters are checked: ➢ Voltage on L1 input → associated with V1 ➢...
  • Page 57 PQA924 Fig. 74: Autoset execution with connection errors (clamps reversed) 11. The Fig. 75 – left part shows the error condition described in point 8 where the active powers P2 and P3 are negative (the values shown in red are only to highlight the problem).
  • Page 58 PQA924 6.3. STARTING AND STOPPING A RECORDING CAUTION • The instrument can only record when a memory card of the type described in § 9.2 is inserted in the slot (see Fig. 3- Part 2) • Before starting a recording, it is advisable to make a preliminary...
  • Page 59 PQA924 If the instrument detects the presence of negative active powers, the following screen appears on the display when the GO/STOP recording start key is pressed: Fig. 79: Preliminary check on active powers Pressing the "OK" key allows the recording to start, but a preliminary check of the current clamps connected to the installation and running the Autoset function is recommended (see §...
  • Page 60 PQA924 6.4. STORED DATA The "Saved Data" section allows you to check the contents of the memory during and at the end of recording, as well as deleting stored measurements, 1. Touch the “Saved Data” icon. The following screen will be displayed Fig.
  • Page 61 PQA924 6.5. INSTRUMENT INFO This section provides the general parameters relating to the internal characteristics of the utility instrument in the event of contact with HT Customer Support. 1. Touch the "Instrument Info" icon. The following screen appears on the display: Fig.
  • Page 62 PQA924 7. CONNECTING THE INSTRUMENT TO A PC The connection between PC and instrument for downloading recorded data can be managed in the following modes: ➢ Via direct access to the memory card connected to the PC with a relative reader (recommended option in case of very large downloading recordings) ➢...
  • Page 63 C2010 cable 3. Launch the HTAgorà software 4. Click on "Scan" to detect the instrument. The "PQA924" and type of connection “USB” are shown, as indicated in the Fig. 84 Fig. 84: Connecting the instrument via the HTAgorà software and USB connection 5.
  • Page 64 RJ45 input connector (see Fig. 2 – part 4), as described in § 5.1.11 3. Launch the HTAgorà software 4. Click on "Scan" to detect the instrument. The row "PQA924" and type of connection “NETWORK” are shown as indicated in the Fig. 86 Fig.
  • Page 65 PQA924 8. MAINTENANCE 8.1. GENERAL INFORMATION During use and storage, the recommendations in this manual must be followed to avoid possible damage or danger to the operator. Do not use the instrument in an environment with humidity or temperature outside the range specified in § 9.3. Do not expose to direct sunlight.
  • Page 66 PQA924 Recharging internal batteries Always use the supplied external power pack to fully recharge the batteries. The external power pack recharges the batteries both when the instrument is on and off. Do not recharge alkaline batteries. Proceed as follows: 1. Remove the cables from the input terminals 2.
  • Page 67 PQA924 9. TECHNICAL SPECIFICATIONS 9.1. TECHNICAL SPECIFICATIONS Accuracy calculated as [reading + value] at 23°C5°C, <70RH. Uncertainties for values outside the indicated recording ranges are not declared AC TRMS (L-L / L-N) Voltage – Class S (IEC/EN61000-4-30) Accuracy Accuracy Class S...
  • Page 68 PQA924 TRMS AC Current (FLEX Transducer – FS=10000A) - Class S (IEC/EN61000-4-30) Range [mV] Resolution [µV] Accuracy 1.7  85.0 (2.0rdg+1400µV) 85.0  850 (2.0rdg) Signal values <1.7mV are reset; Frequency range: 42.5Hz ÷ 69.0Hz; Crest factor: ≤1.8 Inrush currents - (Standard STD Transducer)
  • Page 69 PQA924 Power Harmonics - Class S (IEC/EN61000-4-30) Voltage Current Udin [V] Resolution [W] Accuracy condition condition (20rdg+10dgt) Ih ≥ 10%FS Uh ≥ 3%Udin (0.30FS+10%rdg+10dgt) Ih <10%FS 100 ÷ 690 (0.30Udin+10%rdg+10dgt) Ih ≥ 10%FS Uh <3%Udin (0.30Udin+0.30%FS+10dgt) Ih <10%FS FS = Full scale of the clamp used; Udin = rated system voltage ; Fundamental frequency range: 42.5Hz ÷ 69.0Hz Active/Apparent Power/Energy (V: [80%..120%Udin], I:FS[1..3000A], cos...
  • Page 70 PQA924 AC Reactive Power/Energy (V: [80%..120%Udin], I: FS [1..3000A], cos = 0.5) – STD Clamp Current range Range Resolution Accuracy [mV] [VAr] [VArh] [VAr] [VArh] 0.000 x FS ÷ 9.999 x FS 0.001 x FS 20 100 10.00 x FS ÷ 99.99 x FS 0.01 x FS...
  • Page 71 PQA924 9.2. GENERAL CHARACTERISTICS Instrument functions Periodic analysis (TRMs values): Voltages (5 channels), Currents (4 channels), Active, Reactive, Apparent Powers, Power factors and cos (4 quadrants), Active and Reactive Energies (4 quadrants), Voltage dissymmetry, Flicker, Peak values Harmonic analysis: Voltage...
  • Page 72 PQA924 9.3. ENVIRONMENTAL CONDITIONS FOR USE Reference temperature: 23°C ± 5°C ; (73°F ± 41°F) Working temperature: -10°C ÷ 50°C ; (14°F ÷ 122°F) Relative humidity: 10°C ÷ 30°C → <95%RH (non-condensing) 30°C ÷ 40°C → <75%RH (non-condensing) 40°C ÷ 50°C → <45%RH (non-condensing) Storage temperature: -20°C ÷...
  • Page 73 PQA924 APPENDIX – THEORETICAL OUTLINES 10.1. VOLTAGE ANOMALIES The instrument defines a voltage anomaly as an event in which the TRMS value, calculated on a cycle updated every half cycle, of one or more voltages exceeds the set upper or lower threshold.
  • Page 74 PQA924 10.2. VOLTAGE AND CURRENT HARMONICS 10.2.1. Theory Any non-sinusoidal periodic wave can be represented by a sum of sine waves, each with an integral multiple of the fundamental frequency (@50Hz or @60Hz) according to the ratio: ∞  ��(��) = ��...
  • Page 75 PQA924 The EN50160 and IEC/EN61000-4-30 Class S regulations suggest truncating the sum in expression (1) to the 40th order. A fundamental index for detecting the presence of harmonics is the Total Harmonic Distortion (THD% percentage value) parameter, defined This index takes into account the presence of all harmonics: the more distorted the voltage or current waveform, the higher the index.
  • Page 76 PQA924 10.2.3. Causes of the presence of harmonics Any user who modifies the sine wave, or uses only part of it, will cause distortion and therefore introduce a harmonic content. All current signals are somehow virtually distorted. The most common harmonic distortion is caused by NON-LINEAR loads such as appliances, PCs or motor speed regulators.
  • Page 77 K factor is an index that defines its ability to supply a more or less non-linear load, avoiding excessive heating and ensuring continuity of service. It is defined by the following ratio and is a parameter present in the harmonic analysis performed by the PQA924 instrument: ∑ ( ��...
  • Page 78 ➢ Loads based on electric arc technology, such as welding machines and electric arc furnaces ➢ Electric drives ➢ Static converters The PQA924 instrument performs voltage and current interharmonic calculations. A fundamental index for detecting the presence of voltage interharmonics is the Total Interharmonic Distortion paramter, THIV% value, defined as: √∑...
  • Page 79 PQA924 10.3. INRUSH CURRENTS The PQA924 allows you to detect and record events related to the inrush current, a typical phenomenon in the starting of rotating machines, but also used for other types of applications in the industrial plant sector (e.g. troubleshooting of load switches, sizing of protections, oscillating currents, etc.), as shown in the following figures:...
  • Page 80 PQA924 ➢ Detection modes: The following modes are available: Fixed: The instrument detects and stores an event when the RMS value of the current calculated for each period and updated every half period (10ms at 50Hz, 8.3ms at 60Hz) exceeds the value of the user-defined threshold. In order for the instrument to be ready to detect a new event, the current must fall below the value of the set limit threshold.
  • Page 81 Electricity distribution companies must also comply with specific requirements in relation to this disturbance. The PQA924 instrument derives the distorted signal with respect to the ideal one and carries out a statistical analysis from which it derives the following quantities: •...
  • Page 82 3% may occur at the three-phase power terminals.. The PQA924 instrument measures and records the following parameters that define the percentage of unevenness on the voltages of an electrical system: ��...
  • Page 83 PQA924 10.6. FAST VOLTAGE TRANSIENTS The PQA924 instrument saves as fast voltage transients (spikes) all phenomena associated with phase voltages under the following conditions ➢ Fast changes in the slope of the voltage waveform with a sampling time of 1µs with a maximum amplitude of ±8kV...
  • Page 84 PQA924 10.7. CALCULATED NETWORK PARAMETER DEFINITIONS Referring to a generic 3-Phase 4 Wires system, the instrument calculates the values of the network parameters on the basis of Ns samples taken over Nc cycles (10 cycles @50Hz / 12 cycles @60Hz ) of the voltage and current signals using the following ratio:...
  • Page 85 PQA924 Parameter Description Calculation model �� = �� + �� + �� Total Active Power ������ ��1 ��2 ��3 �� = �� + �� + �� Total Reactive Power ������ ��1 ��2 ��3 Total Apparent Power = √( �� + ( ��...
  • Page 86 PQA924 10.7.1. Conventions on powers and power factors The conventions used to identify the type of reactive power, the type of power factor, the direction of active power and the direction of reactive power are shown in the following diagram (according to IEC/EN 61557-12) Fig.
  • Page 87 PQA924 The meaning of the symbols used and the values assumed by them in the diagram above is shown in the following tables: SYMBOL DESCRIPTION NOTES Active power + PFc+ Capacitive power factor + PFi+ Inductive power factor + Positive values for quantities cosc+...
  • Page 88 PQA924 10.7.2. ARON INSERTION In distributed electrical systems without a neutral, phase voltages, power factors and phase cosines lose their meaning and only the phase-to-phase voltages, phase currents and total power remain defined. Phase 1 VAR 1-2 W 1-2 Three-phase...
  • Page 89 PQA924 10.8. CONNECTING THE INSTRUMENT WITH EXTERNAL CTS The PQA924 also allows current measurements to be made in three-phase systems (typical of MV/LV systems) where they are present on the lines of Current Transformers (CTs) with a transformation ratio of xxx/1A or xxx/5A.
  • Page 90 PQA924 10.9. MEASUREMENT METHOD The instrument can measure: voltages, currents, active powers, capacitive and inductive reactive powers, apparent powers, capacitive and inductive power factors, energies, etc. All these quantities are analysed digitally (conversion of six analogue signals of voltages and currents) and calculated internally on the basis of the formulas described in the previous sections.
  • Page 91 PQA924 SERVICE 11.1. WARRANTY CONDITIONS This instrument is guaranteed against defects in materials and workmanship in accordance with the General Conditions of Sale. During the warranty period, all defective parts may be replaced and the manufacturer reserves the right to repair or replace the product. If the instrument is to be returned to the after-sales service or to a dealer transportation costs shall be borne by the Customer.
  • Page 92 WHERE T +39 0546 621002 | F +39 0546 621144 WE ARE M ht@ht-instruments.com | www.ht-instruments.it HT INSTRUMENTS SL C/ Legalitat, 89 08024 Barcelona – Spain T +34 93 408 17 77 | F +34 93 408 36 30 M info@htinstruments.es | www.ht-instruments.com/es-es/...