The CENTER 251 is an HVAC Clamp Meter designed for various electrical measurements, including voltage, current, resistance, capacitance, continuity, and temperature. It features a digital liquid crystal display (LCD) with a maximum reading of 6200, providing clear and precise data. The meter is powered by two 1.5V AAA batteries, offering a typical battery life of 50 hours without the buzzer or backlight function.
Function Description:
The CENTER 251 is a versatile instrument capable of performing a wide range of measurements essential for HVAC and electrical diagnostics:
- Direct Voltage (DCV) Measurement: Measures DC voltage up to 600V with a resolution of 0.1V and an accuracy of ±1% + 2 digits. It has an input impedance of 10 MΩ.
- Direct Voltage Peak Measurement: Measures DC voltage peaks up to 600V with a resolution of 0.1V and an accuracy of ±1.5% + 10 digits. Input impedance is 10 MΩ.
- Alternating Voltage (ACV) Measurement: Measures AC voltage up to 600V with a resolution of 0.1V and an accuracy of ±1.2% + 8 digits. Input impedance is 10 MΩ.
- Alternating Voltage Peak Measurement: Measures AC voltage peaks up to 600V with a resolution of 0.1V and an accuracy of ±2.0% + 10 digits. Input impedance is 10 MΩ.
- Direct Current (DCμA) Measurement: Measures DC microamperes up to 600μA with a resolution of 0.1μA and an accuracy of ±1% + 2 digits.
- Direct Current Peak Measurement: Measures DC current peaks up to 600μA with a resolution of 0.1μA and an accuracy of ±1.5% + 10 digits.
- Alternating Current (ACA) Measurement: Measures AC current up to 600A across two ranges: 60A (0.01A resolution) and 600A (0.1A resolution), with an accuracy of ±1.9% + 10 digits.
- Alternating Current Peak Measurement: Measures AC current peaks up to 600A across two ranges: 60A (0.1A resolution) and 600A (0.1A resolution), with an accuracy of ±2.5% + 10 digits.
- Resistance (Ω) Measurement: Measures resistance up to 6.000 KΩ across two ranges: 600 Ω (0.1 Ω resolution) and 6.000 KΩ (0.001 KΩ resolution), with an accuracy of ±1% + 3 digits.
- Continuity Test: Features an Ohm function with a buzzer that sounds continuously if the resistance is under 40Ω, indicating continuity.
- Capacitance Measurement: Measures capacitance up to 4000 μF across two ranges: 400.0 μF (0.1μF resolution) and 4000 μF (1 μF resolution), with an accuracy of ±2.5% + 10 digits.
- Temperature (°C/°F) Measurement: Measures temperature from -50°C to 600°C (0.1°C resolution) with an accuracy of ±1% + 1.5°C, and from -58°F to 999.8°F (0.2°F resolution) with an accuracy of ±1% + 2.8°F.
Important Technical Specifications:
- Display: 4-digit LCD, maximum reading 6200.
- Polarity: Automatic negative signal indication.
- Low Battery Indication: "+" symbol appears on LCD.
- Sample Rate: 2 times/sec for digital data.
- Power Source: 2 x 1.5V AAA batteries.
- Typical Battery Life: 50 hours (without buzzer, backlight function).
- Auto Power Off: After 30 minutes of inactivity (can be disabled by holding "HOLD" button during power-on).
- Over Load Indication: "OL" symbol.
- Maximum Jaw Opening: Ø25 mm.
- Dimensions: 210 x 62 x 36 mm.
- Weight: Approx. 273g (with battery).
- Environmental Conditions:
- Operation Temperature: 0°C to 40°C (32°F to 104°F); < 70% RH.
- Storage Temperature: -10°C to 60°C (14°F to 140°F); < 80% RH.
- Safety Approvals: CE EN61010 600V CAT III, double insulation.
Usage Features:
The CENTER 251 is designed for user-friendly operation with several key features:
- Function Select Dial: A rotary switch allows easy selection of measurement modes (V, A, Ω, °C/°F, capacitance, continuity).
- HOLD Function: Freezes the current displayed value on the LCD. Pressing the "HOLD" button again deactivates this function.
- PEAK Function: Displays and updates the maximum peak value detected. The "PEAK" symbol appears on the display when active.
- BACKLIGHT Function: Activates the display backlight for 30 seconds when the "PEAK" button is pressed and held for 2 seconds or longer, improving visibility in low-light conditions. Pressing and holding again turns it off.
- AC/DC and °C/°F Function Button: Toggles between AC and DC modes for voltage and current measurements, and between Celsius and Fahrenheit for temperature measurements.
- Clamp Opening Handle: Allows for easy opening of the clamp jaws to encircle a cable for current measurement.
- Input Terminals: Dedicated "COM" (common) and "+" (positive) input terminals for test leads.
- Safety Precautions:
- Always ensure the meter body and test leads are intact before use.
- Set the function dial to the correct position for each measurement.
- Avoid resistance and continuity tests on live power systems.
- Do not exceed maximum voltage limits between terminals and ground.
- Keep fingers behind the protection ring when using test leads.
- Disconnect test leads before opening the case for battery changes or maintenance.
Maintenance Features:
- Battery Changing: The low battery indication ("+" symbol) prompts battery replacement. To change batteries, switch the main dial to "OFF," disconnect test leads, open the back cover with a screwdriver, replace the two 1.5V AAA batteries, and fasten the screw.
- Cleaning: Periodically wipe the case with a dry cloth. Abrasives or solvents should not be used.
- Storage: For long-term storage, remove the batteries and store the meter in an environment free from high temperatures and humidity.
- Accuracy for Current Measurement: For more accurate current readings, position the cable at the center of the clamp.
- Repairs: Repairs or servicing not covered in the manual should only be performed by qualified personnel.
- Circuit Board Protection: To prevent contamination or static damage, avoid touching the circuit board without proper static protection.
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