KPM LA103 PRO Analyzer

The KPM LA 103 Pro is a leakage current analyser for metal oxide surge arresters, the lightning arresters (LAs) installed across substations and HV transmission networks. It checks their condition periodically while they stay in service.It measures the arrester's total leakage current and pulls out the small resistive part of it, which is the part that grows as an arrester ages. It then corrects that resistive current to a standard temperature (+20 °C) and a standard voltage (0.7 × the arrester's rated voltage), so results taken on different days and in different conditions can be compared.Everything is built into one rugged case: a 7-inch colour touch screen, a thermal printer, internal memory and a battery that lasts about 6 hours. A separate wireless transmitter lets you take the reference voltage from a PT up to 1,000 metres away.Picture filekpm-la103pro-lightning-arrester-tester.jpgAlt textKPM LA 103 Pro lightning arrester tester in its rugged case with the wireless signal transmitterCaptionThe LA 103 Pro main test unit (left) and the wireless signal transmitter (right).

Yes, and that is the point of the KPM LA 103 Pro. The test is done with the arrester energised and in normal service.You clip the current lead onto the arrester's earth connection (at the surge counter) using a hot stick, and the instrument analyses the small current flowing to earth. The leads only ever connect to low-voltage points: the earth cable and, in some modes, a PT secondary. Nothing connects to the high-voltage side.You still work within your substation's safe approach distances, and you never test during a thunderstorm or when switching over voltages are likely.

It tests metal oxide surge arresters (MOSAs) of any make, provided:•     the arrester stands on an insulated base, and•     it is earthed through a single grounding wire, preferably insulated, that you can clip onto.It cannot test arresters that are bolted directly to the substation earth with no separate ground lead. With no single earth path to measure, there is nowhere for the instrument to pick up the arrester's leakage current.In a laboratory, an arrester without a surge counter can be stood on an insulating plate and the current taken from its lower end.

•     Main test unit•     3 current input leads (one per phase, colour-coded)•     1 voltage input lead•     1 ground lead•     Main test unit charger•     Wireless signal transmitter and its charger•     2 antennas (one for the main unit, one for the transmitter)•     2 rolls of printer paper•     Stylus pen•     Accessory bag•     Operating manual•     Calibration certificate

1.     Reference voltage terminal: the voltage lead (PT secondary) or the field probe plugs in here.2.     IA leakage current input (yellow, phase A).3.     IB leakage current input (green, phase B).4.     IC leakage current input (red, phase C).5.     Antenna port, for wireless Signal mode.6.     Protective ground terminal: always connected first.7.     Power switch.8.     12.6 V DC charging port.9.     RS-232 port.10.  USB port, for exporting results to a flash drive.11.  Built-in thermal printer.12.     7-inch HD colour touch screen.Picture filela103pro-main-test-unit-panel-layout.pngAlt textPanel layout of the KPM LA 103 Pro main test unit with numbered terminals, ports, printer and touch screenCaptionMain test unit panel, numbered as in the list.

It sends the PT secondary voltage to the main unit by radio. In a big substation the PT marshalling box can be a long way from the arresters you are testing; instead of running a long voltage lead, you connect the transmitter at the PT and carry the main unit to the arresters. The wireless link reaches up to 1,000 metres.The transmitter has its own battery, charger and antenna, plus a protective ground terminal and three indicators: transmitting, low battery and power. It is used in Signal mode (see section C).Picture filela103pro-wireless-signal-transmitter-panel.pngAlt textPanel of the LA 103 Pro wireless signal transmitter with ground, antenna, indicators, power and reference voltage terminalCaptionSignal transmitter: ground, antenna, transmit / low battery / power indicators, power switch, charging port and reference voltage terminal.

The resistive current through a metal oxide arrester is non-linear, so it is distorted rather than a clean sine wave. That distortion shows up mainly as a third harmonic in the leakage current. The manual describes the third-harmonic content as an index of the arrester's degradation: the more degraded the arrester, the larger it becomes.The KPM LA 103 Pro amplifies the current picked up by the lead, filters out the third-harmonic component and works out the total leakage current and the resistive current from it.There is one catch. The system voltage itself can contain some third harmonic, which also drives third-harmonic current through the arrester and can make a healthy arrester look worse. Cable mode measures the voltage as well and compensates for that (see section C).

Resistive leakage current rises with temperature and with the voltage across the arrester. Test the same arrester on a hot afternoon and a cool morning, or at slightly different system voltages, and you get different numbers even though nothing has changed.The KPM LA 103 Pro removes those effects. The manual states that all its test modes can be normalised to a standard ambient temperature of +20 °C and to 0.7 × the arrester's rated voltage, based on the temperature and operating voltage during the field measurement. The result is Ir corr, and it is the figure to record and trend. Measurements made under different conditions can then be compared directly.

Pick the mode by where you can get a voltage reference:•     Standard mode: current lead only, no voltage reference. Quickest; single phase only.•     Cable mode: a voltage lead to the PT secondary gives a reference voltage. Most accurate and best at rejecting interference. Single or three-phase.•     Signal mode: like Cable mode, but the PT voltage reaches the tester by radio from up to 1,000 m away. Single or three-phase.•     FP mode: a field probe at the base of the middle arrester senses the electric field instead of using a PT. Use it when no PT secondary is accessible. Single or three-phase.Select the mode with Func on the main screen. If a Standard mode result looks doubtful, the manual recommends repeating the test in Cable mode.Picture filela103pro-func-menu-test-modes.pngAlt textLA 103 Pro Func menu listing Standard mode, Cable mode, Signal mode, FP mode, Query, Set time and LanguageCaptionChoose the test mode from the Func menu.

Standard mode needs just one current lead and no voltage reference. Plug the green lead into the IB socket first, then clip its other end onto the arrester's earth cable at the surge counter with a hot stick. The instrument analyses the third-harmonic content of the leakage current to work out the resistive current.It is the quickest method and is good for routine screening. Its limits:•     single-phase tests only;•     it cannot see the system voltage, so third harmonic in the supply cannot be compensated.If a result looks unusual, repeat the test in Cable mode before drawing conclusions.Picture filestandard-mode-surge-arrester-leakage-current-connection.pngAlt textStandard mode connection: green current lead clipped to the phase B arrester earth cable at the surge counterCaptionStandard mode: one green current lead on the arrester's earth cable, plus the ground lead.

Accuracy. In Cable mode, the voltage lead takes the PT secondary voltage as a reference while the current lead measures the arrester's earth current. With the actual voltage in hand, the instrument:•     measures the third-harmonic content of the system voltage and compensates for it, so supply harmonics are not mistaken for arrester deterioration;•     rejects interference from the test site, giving accurate and stable readings.Use Cable mode for important arresters, for baseline readings, and whenever a Standard mode result is in doubt. It works for a single arrester or all three phases.Picture filecable-mode-single-phase-arrester-test-connection.pngAlt textCable mode single-phase connection with the voltage lead on the PT secondary and the green current lead on the arrester earth cableCaptionCable mode: voltage lead to the PT secondary, current lead to the arrester's earth cable.

Signal mode works like Cable mode, but the reference voltage travels by radio. Use it when the PT secondary is far from the arresters or awkward to reach.1.     Fit the antennas to both the main unit and the signal transmitter.2.     At the PT: plug the voltage lead into the transmitter's Ref Voltage terminal. Clip the green clamp to the B-phase PT secondary and the small black clip to neutral (N) or the secondary's grounding point. If the secondary has no grounding point, leave the black clip unconnected.3.     At the arresters: connect the current leads to the main unit, matching colours.4.     On the main unit, choose Func → Signal mode.Range is up to 1,000 metres. For a single-phase test select Phase B and use the green current lead and the green voltage clamp. For three-phase tests only 1PT is available; 3PT is not.Picture filesignal-mode-wireless-arrester-test-connection.pngAlt textSignal mode connection: voltage lead on the PT secondary connected to the wireless signal transmitter, current leads on three arrestersCaptionSignal mode: the transmitter at the PT sends the reference voltage by radio. The diagram shows the full voltage lead; for three-phase tests only the green (B-phase) clamp is used (1PT).

FP mode needs no voltage connection at all. A magnetic-mount field probe placed at the base of the arrester senses the electric field there. The instrument uses that as its reference, works out the voltage from it, and analyses the resistive current from the leakage current measured on the earth cable.Two placement rules decide whether the result is right:•     Put the probe at the base of the B-phase arrester, the one in the middle. The manual marks this as very important.•     Keep the plane of the probe parallel to the ground.Place it with an insulating (hot) stick and plug its lead into the Ref Voltage terminal. The probe works over an electric field of 30 to 300 kV/m. FP mode is for when no PT secondary is accessible; it can test one arrester or all three phases (1PT only).Picture filefp-field-probe-mode-arrester-test-connection.pngAlt textFP mode connection with the field probe placed at the base of the phase B arrester and current leads on all three arrestersCaptionFP mode: the field probe sits at the base of the middle (B-phase) arrester.

Both test all three arresters, A, B and C, in one go.•     1PT takes only the B-phase PT secondary voltage as the reference for all three phases. Green clamp on the B-phase secondary, small black clip on neutral (N). Fewer connections.•     3PT takes the A, B and C PT secondary voltages separately: yellow, green and red clamps on phases a, b and c, black clip on neutral.In 3PT the colours must match all the way through. If the yellow voltage clamp is on the A-phase PT secondary, the yellow current lead must be on the A-phase arrester and plugged into the yellow IA socket.3PT is available in Cable mode only. Signal and FP modes offer 1PT for three-phase tests.Picture filecable-mode-three-phase-3pt-arrester-test-connection.pngAlt textCable mode three-phase 3PT connection with yellow, green and red voltage clamps on the PT secondary and matching current leads on the arrestersCaption3PT: each phase's PT voltage paired with the same-coloured current lead.

When three arresters are tested together, neighbour phase compensation corrects each phase's result for the influence of the neighbouring phases. The instrument applies it automatically in three-phase tests once it is enabled.The rule from the manual is simple: whenever you test three phases, set Phase comp. to ON. The manual's single-phase settings for Signal and FP modes also show Phase comp. ON.Picture filela103pro-cable-mode-settings-1pt-3pt-phase-comp.pngAlt textLA 103 Pro Cable mode settings screen with 1PT, 3PT, Once, Sync, PT ratio, compensation angle and Phase comp ONCaptionPhase comp. ON for every three-phase test.

Before you start:•     No thunderstorms in the area, and no switching likely to cause over voltages.•     The arrester stands on an insulated base and is earthed through a single grounding wire.•     You and the instrument stay within the published safe approach distances to live conductors.•     The earthing point is clean: scrape off any paint or rust where the ground lead will connect.•     The KPM LA 103 Pro is connected to the substation earth with the supplied ground lead before anything else.Remember that the instrument is for low-voltage connections only. None of its leads may ever touch high voltage.

The manual's rule for every mode: connect the supplied ground lead from the instrument's ground terminal to the substation grounding system before testing, and after the measurement remove it last.That way the instrument is never connected to the arrester circuit or a PT secondary without its protective earth. If there is paint or rust on the grounding point, remove it first so the connection is sound.

1.     Plug the current lead into the instrument first: IA (yellow), IB (green) or IC (red).2.     Then, using a hot stick, clip its other end onto the arrester's earth cable at the upper end of the surge counter for the phase under test.3.     Match colours: the yellow lead goes to the yellow IA socket, and so on.Do not use extension cables for the current leads.In a laboratory, an arrester without a surge counter can be stood on an insulating plate and the current taken from its lower end.

1.     Plug the voltage lead into the instrument's Ref Voltage terminal.2.     Clip the green clamp to the B-phase PT secondary for single-phase and 1PT tests (the manual's single-phase procedures always test Phase B). For 3PT, clip the yellow, green and red clamps to phases a, b and c. Clip the small black clip to the PT secondary's ground or neutral (N).Two warnings from the manual:•     Check the wiring carefully so you do not short-circuit the PT secondary.•     Never swap the voltage and current leads. A current lead connected to a PT secondary or a test transformer's output can blow the instrument.The reference voltage input accepts 25 to 250 V RMS at 50 or 60 Hz.

Example: Standard mode on the B-phase arrester.1.     Connect the ground lead. Plug the green current lead into IB, then clip it onto the B-phase arrester's earth cable with a hot stick.2.     Switch on. On the main screen tap Func and choose the test mode.3.     Single phase: Phase B.4.     Test method: Once.5.     PT ratio: leave at 1.0. Comp. angle: leave at 0.0.6.     Operating voltage (Standard mode only): tap the field and choose the system voltage, for example 110 kV, then tap Yes.7.     Tap Start. A progress bar shows the test running; the result screen appears when it finishes.8.     Tap Save, or the result will not be stored.Picture filela103pro-main-test-screen.pngAlt textLA 103 Pro main test screen with single phase, test method, PT ratio, compensation angle and operating voltage fieldsCaptionMain test screen: phase, test method, PT ratio, compensation angle and operating voltage.

Use a three-phase test in Cable mode (1PT or 3PT), Signal mode or FP mode (1PT).1.     Connect the ground lead.2.     Connect the three current leads to the three arresters' earth cables, colour-matched: yellow to A, green to B, red to C.3.     Connect the voltage reference for the chosen mode.4.     On the settings screen leave Single phase unselected, and choose 1PT or 3PT under 3-phase test.5.     Test method: Once. PT ratio 1.0 and Comp. angle 0.0 (defaults).6.     Phase comp.: ON.7.     Tap Start. The instrument tests arresters A, B and C in turn and shows all three results on one screen.Picture filecable-mode-three-phase-1pt-arrester-test-connection.pngAlt textCable mode three-phase 1PT connection with current leads on all three arresters and the green voltage clamp on the B-phase PT secondaryCaptionThree-phase 1PT test: three current leads, one PT reference.

•     Once: one measurement, then the result screen.•     Sync: continuous measurement that keeps updating until you tap Stop or the battery runs out.Once is the normal choice for recording results. Sync is useful for watching a reading settle, or for seeing how it changes while you check a connection.

In Standard mode there is no voltage lead, so you tell the instrument the system's operating voltage. It is used to correct the resistive current to the standard reference of 0.7 × the arrester's rated voltage. Choose the wrong system voltage and the corrected value, Ir corr, will be wrong too. The Cable, Signal and FP setting screens have no operating voltage field.Voltages offered: 15, 35, 60, 66, 110, 132, 150, 220, 230, 330, 380, 400 and 500 kV. Tap the voltage, then Yes, then Start.Picture fileKPM la103pro-set-operating-voltage-15kv-to-500kv.pngAlt textKPM LA 103 Pro set test voltage screen with system voltages from 15 kV to 500 kVCaptionChoose the system voltage from 15 kV to 500 kV.

Yes. Tap Wiring Ref at the bottom right of the main screen to see the reference connection diagram. It is a quick check before you clip on, especially for three-phase and 3PT tests where colours must match.

Yes. Stand an arrester without a surge counter on an insulating plate and take the current signal from its lower end.

•     Ir corr: the corrected resistive current, normalised to +20 °C and 0.7 × rated voltage. The headline figure, and the one to trend.•     Ir: the resistive leakage current as measured, before correction.•     It: the total leakage current.•     Ut: the reference voltage. In Cable and Signal modes it is the PT secondary voltage; in FP mode it is calculated from the electric field captured by the probe.The right-hand side shows the test number, test mode, phase, angle and LSC (surge counter reading). The keys at the bottom are Save, Print and Back, and the arrow opens a detail page with harmonics.

The temperature shown comes from a sensor inside the instrument, so it reads the instrument's own temperature, not necessarily the air around the arrester. The manual says the ambient temperature needs to be entered for the temperature correction.So check it on every test: tap Temp, type the actual ambient temperature and tap YES. The LA 103 Pro recalculates Ir corr straight away using the value you entered.Picture filela103pro-enter-ambient-temperature-correction.pngAlt textKeypad on the LA 103 Pro result screen for entering the ambient temperatureCaptionTap Temp, type the ambient temperature and tap YES to recalculate Ir corr. Layout from the manual; the example values are placeholders, not a real test.

Tap the arrow on the result screen to open it. Three columns plus a summary:•     Voltage: Ut (test voltage RMS); U1 (fundamental; close to Ut when harmonics are low); U3 to U7 (3rd, 5th and 7th harmonics relative to U1).•     Total current: It (RMS), Itp (peak), It1 to It7 (peaks of the 1st, 3rd, 5th and 7th harmonics).•     Resistive current: Ir (RMS), Irp (peak), Ir1p to Ir7p (peaks of the 1st, 3rd, 5th and 7th harmonics), Ic1p (peak of the capacitive fundamental).•     Summary: test number, Cx (capacitance), phase, Φ0 (compensation angle), Ku (PT or test transformer ratio), F (grid frequency). The page also shows Φ and P, which the manual does not define; the printout shows P in mW.These figures help when a result needs explaining, for example whether supply-voltage harmonics are high.Picture filesurge-arrester-leakage-current-harmonics-detail-page.pngAlt textLA 103 Pro detail page with voltage, total current and resistive current harmonics, capacitance, compensation angle, ratio and frequencyCaptionDetail page, opened with the arrow on the result screen.

•     LSC is the reading on the arrester's surge counter, typed in by hand.•     Test No. is the test ID. Tap the box and type a name that identifies the arrester, for example its bay and phase.Neither is measured, but both turn a number into a record. With them, each saved result can be traced to a specific arrester and set against how many surges it had seen at the time

Each column is one arrester (Phase A, B, C), with Ir corr, Ir, It, Ut and the angle Φ for each.The panel on the right shows the temperature box (tap to enter ambient temperature), the three phase voltages Ua, Ub and Uc, three further angle readings (Φa_b, Φb_c, Φc_a), the test number and LSC.Seeing the three arresters side by side is a useful check in itself: arresters of the same type in the same bay should read similarly, and one that stands out deserves a closer look.Picture filethree-phase-surge-arrester-test-results.pngAlt textLA 103 Pro three-phase result screen with Ir corr, Ir, It, Ut and angle for phases A, B and CCaptionThree-phase results side by side.

Standard mode works from the leakage current alone, so it cannot tell third harmonic caused by the arrester from third harmonic caused by distortion in the system voltage. Cable mode measures the PT secondary voltage too, compensates for the voltage harmonics and rejects site interference.So when the two disagree, trust Cable mode. The manual's advice: if there is any doubt about a Standard mode result, repeat the test in Cable mode.

Most likely it was never saved. The KPM LA 103 Pro does not save results automatically: at the end of every test you must tap Save on the result screen to store it in internal memory. Tap Back without saving and the result is gone.Make tapping Save part of every test, before Print or Back.

On the main screen tap Func, then Query. Saved results are listed in order of test time.•     Use the arrows to scroll.•     Tap the small dot after a file to select it; the dot changes colour when selected.•     View opens the selected result; Delete removes it; Back returns to the main screen.Picture filela103pro-query-saved-results-usb-export.pngAlt textLA 103 Pro Query screen listing saved test files with options to save to USB key or to the appCaptionQuery: saved tests in time order, with export options.

1.     Open Func → Query.2.     Select the results you want by tapping the dot after each one.3.     Tap the USB key icon to save the selected files to a USB flash drive in the USB port.The Bluetooth icon saves selected files to the companion app, an optional feature. Ask KPM whether it is enabled on your unit.

Yes. Tap Print on the result screen and the built-in thermal printer prints the test data, including the date and time, test mode, phase and results. The kit includes two paper rolls.If the printer does not work, check that the paper roll is fitted correctly and the battery is not low.Picture filela103pro-built-in-thermal-printer-printout.pngAlt textLA 103 Pro built-in thermal printer with a sample printout showing date, mode, phase and resultsCaptionBuilt-in thermal printer and a sample printout.

•     Date and time: Func → Set time. Results are stamped with the date and time, so set them correctly before testing.•     Language: Func → Language switches between English and Chinese firmware.•     Bright sun: the icon at the bottom left of the main screen switches between the standard display and a daylight display that is easier to read outdoors.

The 11.1 V, 5,200 mAh lithium battery gives about 6 hours of continuous testing. A full charge from empty takes about 4 hours, longer if you use the instrument while charging.Charge through the 12.6 V DC charging port using the original charger, which runs on 100–250 V AC, 50/60 Hz. The unit may feel warm while charging, even when switched off. Unplug the charger before packing the unit into its case, to avoid overheating.The signal transmitter has its own battery and charger; charge it before a Signal mode job.

•     Charge and discharge the battery every 3 months, even if the instrument is not in use. A charged battery slowly discharges itself over time.•     Use only the original charger and battery. Never use a damaged or worn adapter or battery.•     Let the instrument return to room temperature before using or charging it. Extreme heat or cold affects charging, and storing the battery in extreme temperatures reduces its capacity and life.

The manual warns that plugging or unplugging test leads while voltage and current are applied can blow the instrument. A lead clipped onto a live earth cable or PT secondary carries a signal whether or not a test is running.•     Connecting: plug the lead into the instrument first, then clip it on.•     Disconnecting: unclip it first, then unplug it from the instrument.

The instrument can be damaged. The manual warns that if a current test lead is connected to a PT secondary voltage or to the output of a test transformer, the instrument may blow.Keep the two lead types apart: current leads go to the IA, IB and IC sockets and the arrester earth cables; the voltage lead goes to the Ref Voltage terminal and the PT secondary. Check before switching on.

From the manual's troubleshooting table:•     No display after switching on: battery flat, or a processor fault.•     LCD does not display: low battery, or a processor fault.•     Battery won't charge: blown fuse, faulty charging circuit, or damaged battery.•     Printer doesn't work: paper not fitted correctly, low battery, printer fault or processor fault.Charge the battery and check the paper first; they solve most cases. If the instrument still does not work, see the next question.

The manual gives two causes:•     A clip is not properly fastened on the earth cable or the PT terminal.•     A test lead is damaged (blown).Reseat every clip firmly on clean metal, then try a spare lead if the problem stays.

1.     Stop using it immediately and tell KPM.2.     Check whether the fuse has blown. If it has, replace it with a fuse of exactly the same specification, and you can carry on testing.3.     If it still does not work, contact KPM directly.Do not open the instrument or try to repair it yourself.

Partly. With the lid closed, the case is rated IP67: dust-tight and protected against temporary immersion, which protects the instrument in transport and storage. With the lid open for testing the rating is IP40, which gives no protection against water, so do not test in rain.Working conditions: −10 to 50 °C and 20–80% relative humidity. Store between −20 and 70 °C. Avoid leaving it in hot, humid places.Never test when there are thunderstorms in the area, whatever the weather where you are standing.

Measurement:•     Total leakage current: 0–20 mA RMS, 50/60 Hz; accuracy ±(5% rdg + 5 µA)•     Resistive current: 0–10 mA•     Standard mode accuracy: ±(5% rdg + 10 µA)•     Cable mode: resistive current fundamental accuracy ±(5% rdg + 5 µA); reference voltage input 25–250 V RMS, 50/60 Hz, accuracy ±(5% rdg + 0.5 V)•     FP mode: electric field input 30–300 kV/m, accuracy ±5% rdg•     Wireless range (Signal mode): up to 1,000 mInstrument:                   •     7-inch HD colour touch screen•     Power: 12.6 V DC or 100–250 V AC, 50/60 Hz•     Battery: 11.1 V, 5,200 mAh lithium; about 6 hours continuous; about 4 hours to charge•     Internal memory with time and date stamp; built-in thermal printer; USB and RS-232 ports•     Size 35 × 28 × 18 cm; weight 3.8 kg including battery•     Working −10 to 50 °C, 20–80% RH; storage −20 to 70 °C•     Protection IP67 (lid closed), IP40 (lid open)•     Standard: IEC 60099-5