UNI-T UT18A Voltage e Tester de continuidade

Introdución

• The UNI-T UT18A is a professional-grade voltage and continuity tester designed for electricians, maintenance technicians, and other tradespeople. It provides quick LED-based (and in certain models: LCD) indication of AC/DC voltages, phase rotation in three-phase systems, polarity, and continuity, all within a compact pen-style form factor.
• Its design emphasizes safety (up to CAT IV 600 V) and versatility, making it suitable for industrial and commercial environments.

ESPECIFICACIÓNS

• Voltage measurement range: up to approx 690 V AC/DC (for this series)
• Input protection: 600 Vrms (for some versions)
• Sobrevoltage protection: ~750 VAC/DC for UT18A/B/C; other models go higher.
• Continuity test: 0 Ω…100 kΩ (approx) with buzzer & LED indicator
• Phase rotation test: 57 V-400 V (three-phase) for supported versions.
• Dimensions: 272 × 85 × 31 mm (approx)
• Battery: 2 × AAA (or IEC LR03) cells
• Safety category: CAT IV 600 V / CAT III 690 V (per series)
• Other features: LED indication, polarity detection, “no power” detection (voltage detection even without battery) on some models.

Uso

1. Voltage cheque: Connect the two test leads (or test pens) to the circuit or conductor you wish to test. The UT18A will light the corresponding LED(s) to indicate approximate voltage level. For AC/DC voltages up to ~690 V, it will indicate. (Always check actual manual for exact model limits.)
2. Polarity check: For DC circuits, the tester will indicate positive vs negative polarity (depending on model) when the probes are connected.
3. Proba de continuidade: With the circuit de-energised, connect the leads across the component or conductor. A continuity LED and audible buzzer will indicate if resistance is within the continuity threshold (e.g., < 100 kΩ).
4. Phase rotation / three-phase test: In three-phase AC systems, the device can help indicate phase rotation or sequence by connecting between phases (depending on model support).
5. “No-power” detection: Some versions of the UT18 series allow basic voltage presence indication even if the internal battery is exhausted (voltage detection circuit still active) — helpful for checking live circuits when the tester battery is low.

Seguridade

• Always assume a conductor is live until proven otherwise, and use the tester accordingly.
• Ensure you are using the tester within its rated category and voltage (e.g., CAT IV 600 V) environment. Using the rating above can lead to hazard.
• Wear appropriate personal protective equipment (PPE) when working on live circuits (gloves, eye protection, insulated tools).
• Before maintenance or continuity testing, make sure the circuit is de-energised and properly isolated.
• Connect the probes securely and avoid contact with exposed conductors. Do not hold the metal probe tips when measuring live circuits — hold only the insulated portion.
• The manual emphasises not using the instrument if it appears damaged, and maintenance/cleaning should be done while the tester is disconnected from any live circuit
• Check and replace batteries when low battery indication appears. A fatigued battery may cause unreliable readings.

Símbolos referidos no manual

• The manual includes necessary information regarding the safe usage and equipment maintenance and, before use, read through each section of the manual.
• Non ler o manual ou non comprender o método de uso do equipo especificado no manual provocaría danos físicos e danos ao equipo.

Símbolo no panel do probador e a súa descrición (Figura 1)

1. Test pen L 1;
2. Test pen L2;
3. Voltage indicación (LED);
4. pantalla LCD;
5. Vol. Altotage indicación;
6. AC indication;
7. Indicación de continuidade;
8. Polar indication;
9. Rotary phase indication:
10. RCD indication (LED);
11. RCD test button:
12. Flashlight/self-inspection button;
13. HOLD mode/backlight button;
14. Lanterna
15. Test pen cap;
16. Tapa da batería

A Figura 2 ofrece unha descrición detallada do panel LCD.

1. Indicación de modo silencioso;
2. indicación do modo HOLD;
3. Baixo voltage indicación de batería;
4. Voltage medición;
5. Medición de frecuencia;
6. DC voltagmedición
7. AC voltage medición;
8. Voltage indication (LCD segment code);
9. Vol. Altotage indicación;
10. Indicación de continuidade;
11. indicación RCD;
12. Indicación de fase rotativa

Instrución de funcionamento e ámbito de uso do comprobador

• Voltage and continuity tester includes four models: UT18A, UT 18B, IJT18C and UT18D, has such functions as ACIDC (including three-phase alternating current) voltage measurement, three-phase AC phase indication,  frequency measurement, RCD test, continuity test, the simple test in case of no battery power supply, self-inspection, silent mode choice, overvoltage indicación e baixo voltage indicación de batería. Ademais, a lanterna unida ao bolígrafo de proba proporciona unha aplicación cómoda nun ambiente escuro.
• To protect tester and, more particularly, the tester user, the tester is equipped with protecting jacket. The tester should be put on protective jacket after use and, preferably, placed inside tool kit so as to protect it against any damage. Never place the tester into your pocket
• O probador é aplicable a varias ocasións, como a casa, a fábrica, o departamento de enerxía eléctrica, etc.

lt has the following characteristics:

1. Para protexer as lesións físicas, está deseñado cunha chaqueta protectora;
2. LED indication (UT18NB/C);
3. LCD voltage and frequency display (UT18C/D);
4. AC/DC medido ata 690V;
5. Medición de continuidade;
6. Indique as relacións de fase entre CA trifásica;
7. Tanto o modo zumbido como o modo silencioso son opcionales;
8. Detection without battery (UTI 8A/B/C);
9. Illumination function;
10. función de autoinspección;
11. Vol. de batería baixatage indicación e vol. medidotage over range indication;
12. RCD test (UT18B/C/D);
13. Modo de espera automático.

Voltagmedición

• Observe as normas de proba de seguridade especificadas no punto 3.

Voltage gear of tester is composed of a line of LED or LCD segment codes, including 6V (UT18D), 12V, 24V, 50V, 120V.230V, 400V and 690V. LED (or LCD segment code) would be lighted one after another along with increased voltage, así como a indicación de LED de polaridade (ou código de segmento LCD), indicación LED AC (ou código de segmento LCD), indicación LED de encendido-apagado (ou código de segmento LCD), indicación LED RCD (ou código de segmento LCD), fase rotativa Indicación LED (ou código de segmento LCD) e alto voltage Indicación LED (ou código de segmento LCD).

1. Complete self-check of tester before test. After pressing flashlight key 5s, tester would perform AC/DC  full range detection, accompanied by flashing LED (with exception to RCD light) and blinking displayed  LCD. If need to exit self-check, just touch the flashlight key. Connect two test pens to the conductor to be measured, select a known voltage for measurement, such as 220V socket, and ensure the measurement accuracy (See Figure 3), The tester cannot measure AC and DC voltage menos de 5 V e non proporciona indicación precisa mentres se mide o voltage é 5Vac/dc. Luz de continuidade iluminante ou luz de CA ou de alto voltage symbol (IJT18D) and beeping buzzer are normal.
2. Tester would provide LED indication (UTI 8NB), LED+LCD indication (UT18C) and LCD indication (UT18D) while measuring AC or DC voltage. Alto voltagO LED iluminarase e o zumbador emitirá un pitido cando se mida o voltage é un volume extra baixotaglimiar e (ELV). Se se mide voltage segue aumentando e superando a protección de entrada voltage (750Vac/dc) of the tester, 12\E690V LED would keep flashing (IJTI 8A/B/C), LCD displays “OLP (UT18C/D) and buzzer keeps beeping.
3. Para medir DC voltage, if 1-2 and Ll is connected respectively to the positive and negative pole of the object to be measured, LED would indicate the corresponding voltage, LCD mostra o voltage, meanwhile the LED indicating positive pole would be illuminated, LCD displays “+9 “VDC” and, on the contrary, the LED indicating negative pole would be illuminated, LCD displays “-“”VDC”. If need to judge the positive and negative pole of the object to be measured, connect two test pens to the object to be measured randomly, the illuminating positive pole LED or LCD “+” on tester means the terminal connecting to L2 is the positive and the other connecting to Ll is the negative.
4. Para medir AC voltage, two test pens may be randomly connected to two ends of the object to be measured, AC LED would be illuminated, LCD displays “VAC” while LED indicates the corresponding voltagO valor e mostra LCD correspondentes voltage valor.
   Nota: Para medir AC voltage, L and R phase inversion indication LED (UT18A/B/C) or L and R symbol (UT18D) would be illuminated, it means phase indication is unstable, L light (L symbol) or R light (R symbol) is illuminated, and even L and R light (L and R symbol) would be illuminated alternatively; L and R light (L and R symbol) would not provide correct and stable indication unless measuring three phase power system.

Detección sen batería
O comprobador pode realizar unha detección sinxela mentres a batería se esgota ou non se proporciona. Conecte dous bolígrafos de proba ao obxecto a medir, cando o obxecto teña un voltage higher than or equivalent to 50V AC/120V DC, high -voltagO LED estaría iluminado, indicando un volume perigosotage e o LED iríanse iluminando gradualmente xunto co aumento do volumetage to be measured. The function is applicable only to UTI 8A/B/C.

Proba de continuidade
Para confirmar se o condutor que se vai medir está electrificado, voltage measurement method may be adopted to measure voltage at both ends of the conductor by using two test pens. Connect two test pens to the both ends of the object to be measured, if the resistance falls within O 100kQ, continuity LED (UT18NB/C) or continuity symbol ” (UT18D) would be illuminated, accompanied by continuous beeping buzzer; and if resistance falls within 100kQ 150kQ, continuity LED (UTI 8A/B/C) or continuity symbol “ (UT18D) may or may not be illuminated and buzzer may or may not beep: if resistance is >150kQ, continuity LED (UTI 8NB/C) or continuity symbol ” ” (UT18D) may not be illuminated and buzzer would not beep. Before any test, be sure the object to be measured is not electrified.

Proba de rotación (indicación de fase AC trifásica)

• A The measurement must be conducted in accordance with the safety test regulations specified in item 3.
• Aln the case of strong electric field interference or strong radiation test phase sequence, the test results may be unstable.
• O LED R, L ou o símbolo L e R é aplicable para a proba de rotación e a proba só é aplicable ao sistema de CA trifásico.

1. Trifásico voltage test range: 57V—400V (50Hz—60Hz);
2. Hold the main body of tester (with finger holding handle), as shown in the following figure, connect test pen L2 to any phase and Ll to any of remaining two phases,
3. R or L LED would be illuminated, and after connecting a test pen to another phase, another LED (L or R) would be illuminated,
4. L or R LED would be illuminated accordingly when the position of two test pens are exchanged,
5. LED indicaría o volume correspondentetage ou LCD mostra o volume correspondentetage valor, o vol. indicado ou mostradotage debería ser fase voltage contra terra pero trifásico voltage,

Diagrama das probas do sistema eléctrico trifásico (Figura 4)

Nota: For measuring three-phase AC system, connect three measuring terminals to the corresponding terminal of three-phase system and, since the tester has only two test pen terminals, it is required to form the reference terminal by holding tester handle with finger (through the ground), therefore it would not accurately indicate the phase sequence of three-phase system if not holding the handle or wearing insulating gloves. In addition, it is necessary to ensure  the earth terminal (earth wire or shell) of three-phase system in contact with human body while measuring three-phase power system lower than 100V.

Proba RCD

• Para reducir a perturbación voltage durante o voltage measurement, a circuit with impedance lower than the tester under
  normal measurement mode may be provided between two test pens. namely the RCD circuit system.
• Para a proba de disparo de RCD, conecte dous bolígrafos de proba aos terminales L e PE do sistema de 230 Vca con volta normal.tage measurement mode and press RCD key ” on two test pens, RCD system would trip and the LED indicating RCD (UT18B/C) or  RCD symbol (UT18D) would be illuminated if the circuit then generates AC current higher than 30mA. Particularly, if RCD cannot measure for a long time and, at 230V, the testing time should be <10s, cannot conduct continuous measurement and, after once test, wait 60s before next measurement.

Nota: En caso de non realizar ningunha medición ou proba, é normal ter un LED iluminado continuamente e un pitido continuo despois de premer simultaneamente as teclas RCD en dous bolígrafos de proba. Para evitar trastornos funcionais, non prema dúas teclas RCD no modo de proba non RCD.

Selección do modo silencioso
It is allowed to enter the silent mode while tester is under standby mode or normally used. After pressing flashlight key about Is, tester would bleep and LCD displays silence symbol”” (UTI 8C/D), and tester enters silent mode and, under which mode, all functions are similar to those under normal mode, with exception to the silent buzzer. If need to resume normal mode (buzzing mode), press flashlight key about Is and, after “bleeps”, the silence symbol on LCD would disappear.

Application of illumination function
Illumination function may be selected if need to use the tester at night or in a dark environment; after light touch on flashlight button on tester panel, the headlamp na parte superior do probador acenderíase para facilitar o seu funcionamento e, despois da operación, apague a luz cun lixeiro toque no botón.

Aplicación de retroiluminación (só aplicable para UT18D)
LCD displayed data may be hard to read at night or n a dark environment, allow the display clearly visible by turning on backlight on tester. Backlight would be turned on after pressing HOLD about Is and, after operation, turn off the light after pressing HOLD about Is. If tester enters standby mode while backlight is on, the light would remain illuminated when tester is awakened. The backlight cannot be turned off unless pressing HOLO about is again.

Application of HOLD function (UT18C/D)
Para facilitar a lectura e a gravación, manteña os datos medidos (voltage and frequency value) by a light touch on HOLD on tester while using tester: after another Eght touch, hold status is relieved and restores to normal testing status,

Substitución da batería
Antes de usar o voltage detector , Touch and hold the two probe tips together If shows and you hear the beeper, or in the silent mode ,  on . This makos sure that tho battery courco is not the battery source is exhausted.
Continuously flashing negative LED (IJTI ORB) or low-voltage symbol on LCD (IJTIdC/D) during use of tester indicates low-battery voltage a necesidade de substitución da batería.

Replate battery according to following procedures (as shown in Figure 5):

1. Stop measurement and disconnect Owo test pens from the object measured;
2. Desenrosque os parafusos que fixan a tapa da batería cun desaparafusador;
3. Retire a tapa da batería;
4. Saca a batería para substituír;
5. Install new battery according to the battery symbol and direction indicated on panel: and
6. Insira a tapa da batería e fíxaa con parafusos.

Nota: Para a protección do medio ambiente, as baterías pódense recoller e reciclar nun punto de recollida fixo mentres se elimina a batería ou acumulador desbotable que conteña residuos perigosos.

Siga as normas de reciclaxe válidas locais e elimine as baterías substituídas segundo as regras de eliminación de baterías e acumuladores vellos.

Mantemento de equipos
No special maintenance requirement is provided unless UTI 8A/B/C/D tester should be used as per manual instruction and, in case of any functional abnormality during normal operation, stop using immediately and contact the nearest authorized service center

Limpeza de equipos
Before cleaning, disconnect tester from the circuit being tested. If the instrument gets dirty during normal use. wipe it with wet cloth or small quantity of gentle household cleanser instead of acid cleanser or solvent. Do not use the tester within 5h after cleaning.

Indicador técnico

Funcións especiais

Indicador de precisión da pantalla LCD:

Descrición da función e dos parámetros

• LED voltage range: 12V-690VAC/DC
• LED voltage indication point: 12V, 24V, 50V, 120M 230V, 400V, 690V
• LCD voltage range: 6v–690V AC/DC(UT18C/D); resolution: IV, voltage error: Digits);
• Frequency measurement range: 40Hz—400Hz, resolution: IHz, error: ±(3%+5Digits)
• Voltage measurement: Auto
• Buzzing and silent mode is optional.
• Indicación de polaridade: Auto
• Range selection: Auto
• Response time: LED<O. 1 s/LCD<1 s
• Peak current of test circuit: ls<3.5mA (ac./dc)
• Tempo de proba: 30 s
• Tempo de recuperación: 240 s
• RCD test: Range: 230V (50Hz—400Hz); Current: AC30mA—40mA; Test time <10s, recovery time: 60s;
• Sobrevoltage protection: 750VAC/DC
• On-off test: O kQ…100kQ; Accuracy: Rn+50%;
• Rotation test (three-phase AC): Voltage range: 57V—400V; Frequency range: 50 Hz—60Hz;
• A simple test (without battery): Voltage range: 50VAC&690VAC, 120VDC&690VDC (UT18A/B/C) ;
• Working temperature range: -15 C—+45 °C
• Storage temperature range: -20C—+60 °C
• Working humidity range: S85% RH
• Sobrevoltage protection class: CAT III 690V, CAT IV 600V
• Clase de contaminación: 2
• safety rules IP65 EN61010-1 EN61243-3:2010
• Peso: 238 g (batería incluída);
• Dimensions: 272x85x 31mrn
• Battery IEC LR03 (AAA) x2

TECNOLOXÍA ​​UNI-TREND (CHINA)

• N06, Gong Ye Bei 1st Road,
  Songshan Lake National High-Tech Industrial Development Zone, Dongguan City, Guangdong Province, China
• Teléfono: (86-769) 8572 3888
• http://www.uni-trend.com
• CO, LTD.

Precaucións de seguridade
Para evitar lesións físicas, descargas eléctricas ou incendios, preste especial atención aos seguintes elementos:

• Antes de usar un voltage detector with audible indicator at locations with a high background noise level, it has to be determined whether the audible signal is perceptible. the voltage detectors are designed to be used by skilled persons and in accordance with safe methods of work.
• Os diferentes sinais indicadores do voltagO detector (incluída a indicación do límite ELV) non debe utilizarse para medir.
• Asegúrese de que tanto o bolígrafo como o instrumento de proba estean intactos antes da proba;
• Asegúrese de manter a man só en contacto co mango mentres use o equipo;
• Nunca use o equipo mentres o voltage is beyond the range (referring to technical specification parameters)  and above 800V;
• Antes do uso, asegúrese de que o equipo pode funcionar ben;
• Para garantir o funcionamento normal do comprobador, mida un voltage valor no primeiro.
• O comprobador non se pode utilizar máis en caso de producirse un ou varios fallos funcionais ou sen indicación funcional.
• Nunca proba en condicións húmidas.
• Display functions well only when the temperature ranges -15C —+45 C and relative humidity is
• O instrumento debe ser reparado no caso de que non se poida garantir a seguridade persoal do operador.
• A seguridade deixaría de estar garantida en calquera das seguintes circunstancias:
  1. Visible damage;
  2. Tester’s functions are inconsistent with functions that it supposed to have.
  3. It had been stored in inappropriate conditions for a long time.
  4. Subject to mechanical extrusion in transit.

Preguntas frecuentes

Q1: Can the UT18A measure DC voltage as well as AC voltage?

A1: Yes. The UT18A supports both AC and DC voltage measurements (up to approximately 690 V in many models of the UT18 series). The manual lists AC/DC capability including polarity detection.

Q2: Does the UT18A allow me to test continuity without the internal battery?

A2: The UT18A (and certain models in the UT18 series) features a “no-power” detection mode: even if the internal battery is exhausted, the tester can still give a basic voltage presence indication when voltages exceed a certain threshold (e.g., > 50 V AC/120 V DC). However, for full continuity testing and full functionality you still need the battery.

Documentos/Recursos

UNI-T UT18A VoltagProbador de continuidade e e e [pdfManual de instrucións UT18A Voltage and Continunity Tester, UT18A, Voltage and Continunity Tester, Continunity Tester, Tester

Referencias

• Manual de usuario