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MEGABRAS EM5254 User Manual

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Clamp-on ground resistance tester
• User Manual
• Tecnical specifications

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Summary of Contents for MEGABRAS EM5254

  • Page 1 Clamp-on ground resistance tester • User Manual • Tecnical specifications...
  • Page 2 EM5254 Clamp-on ground resistance tester User Manual GF-2061 © 2018 MEGABRAS. All rights reserved.
  • Page 3 Thank you for purchasing a Megabras Clamp-on Ground Resistance Tester. For best results from your instrument and for your safety, read the enclosed operating instructions carefully and comply with the precautions for use. The- se products must be only used by qualified and trained users.

  • Page 4: Precautions For Use

     PRECAUTIONS FOR USE This instrument and its accessories comply with safety standards EN 61010-1, EN 61010-030, and EN 61010-2-032 for voltages of 600 V in Category IV at an altitude of less than 2000 m with a pollution degree of not more than 2. Failure to observe the safety instructions may result in electric shock, fire, ex- plosion, and destruction of the instrument and of the installations.

  • Page 5: Table Of Contents

    Index Index...........................6 1. Introduction......................8 1.1. Receiving Your Shipment................8 2. Product features.....................9 2.1. Description......................9 2.2. Features......................10 2.3. Applications....................10 2.4. Display......................11 2.5. Control Features...................13 2.6. Audible Signals.....................14 2.7. Rotary Switch Functions................14 2.8. Button Functions...................15 3. Principle of operation...................16 4. Set-up........................18 4.1. Menu Itens....................18 4.2.
  • Page 6 6.1.1.1. Making a Measurement..............30 6.1.1.2. Measurement Results.................31 6.1.2. Advanced Mode..................31 6.1.2.1. Making a Measurement..............31 6.1.2.2. Measurement Results.................32 6.1.3. General Information................32 6.2. Rotary position (A)..................34 6.2.1. Making a measurement.................34 6.3. Rotary position (MR)..................34 6.3.1. Displaying Stored Measurements............34 6.3.1.1. Data Displayed in Standard Mode............34 6.3.1.2.

  • Page 7: Introduction

    1. Introduction 1.1. Receiving Your Shipment Upon receiving your shipment, make sure that the contents are consistent with the packing list. Notify your distributor of any missing items. If the equipment appears to be damaged, file a claim immediately with the carrier and notify your distributor at once, giving a detailed description of any damage.

  • Page 8: Product Features

    The Buzzer and Auto Power OFF features can be disabled at any time. The EM5254 is equipped with an alarm function and a data storage function. In the Alarm mode, the probe will audibly and visually indicate when the rea- ding is beyond an input set point.

  • Page 9: Features

    2.2. Features - Ammeter: Current measurements from 0.2 mA to 40 A. - Loop ohmmeter: Measurement of loop impedances from 0.01 to 1500 Ω The ohmmeter function makes allowance for the presence of inductances in the loop, making impedance measurements more accurate at low values. - Contact voltage: The contact voltage is determined by calculating the pro- duct of the loop impedance and leakage current.

  • Page 10: Display

    2.4. Display The EM5254 is equipped with a 152-segment OLED (organic light-emitting diode) display. This OLED technology results in a thinner, lighter, sharper, higher contrast display compared to LCD displays. Item Description Indicates selection of Advanced mode. In Advanced mode, this indicates when the inductive component is ne- gligible with respect to the resistive component.
  • Page 11 Alarm threshold display: - Display of one of the alarms (1000-count display) with units. - These three digits are also used when configuring the time display mode. (A for A.M., P for P.M. or 24H) in SET-UP (see § 4.4, menu #8). Unit of the alarm displayed.

  • Page 12: Control Features

    2.5. Control Features Figure 2-2 1. Head Assembly: Consists of two individually shielded magnetic cores 2. Guard: Safety guard; do not place hands above this guard 3. Lever: Opens or closes the jaws Toggles display backlight ON/OFF. 5. MEM: Stores measurements into memory. 6.

  • Page 13: Audible Signals

    2.6. Audible Signals There are four audible signals: Type Duration Description Low- Short Normal use (button pressed). pitched Permanent High/Low alarm threshold (Ω, A) triggered. High- Short Abnormal use (for example, memory full). pitched Permanent Alarm threshold (V) exceeded. Audible signals can be enabled or disabled in SET-UP (see § 4.4, menu #2). symbol indicates: Description Buzzer enabled;...

  • Page 14: Button Functions

    2.8. Button Functions Description Button • When the rotary switch is set to Ω+A or A: Increases the brightness of the display, making it easier to read the display in an environ- ment with strong background illumination. Highlighting activated for ▲...

  • Page 15: Principle Of Operation

    3. Principle of operation Typically, a grounded distribution system can be simulated by the basic circuit shown in Figure 3-1 or an equivalent to the diagram shown in Figure 3-2. If voltage (V) is applied to any measured grounding electrode Rx through a spe- cial transformer;...
  • Page 16 Figure 3-1 Figure 3-2...

  • Page 17: Set-Up

    4. Set-up Turn the rotary switch to the SET-UP position. 4.1. Menu Itens The SET-UP position gives access to the following options to set user defined parameters for instrument configuration: Function Erases stored measurements. Enables/disables the buzzer. Enables/disables Auto Power OFF. Sets the impedance alarm threshold (Ω).

  • Page 18: Selecting A Specific Menu

    4.3. Selecting a Specific Menu Use the buttons as follows to select a specific menu item: Button Action ▲ Move up in the menu tree. ▼ Move down in the menu tree. ► Select the menu displayed or return to the previous menu. NOTE: When changes have been made in one of the SET-UP me- nus, the changes can be cancelled by turning the rotary switch to a position other than SET-UP, provided that there has not been a re-...

  • Page 19: Set-Up Menus

    4.4. Set-up Menus Menu # Indication Function Erasing the Memory: ■ Enter the menu by ►. Clr blinks. ■ Press ▲ and ▼ simultaneously for 6 seconds. All re- corded data is erased. The meter indicates MEM 0. ■ Return to the previous menu by ►. Enabling/Disabling the Buzzer: ■...
  • Page 20 Menu # Indication Function Setting the Voltage Alarm Threshold (V): ■ Enter the menu by ►. AL. V blinks. ■ Press ▲ or ▼ to select the state of the alarm (Figure 2-1, item #10): : Disabled. ¯ AL. V ¯...
  • Page 21 Menu # Indication Function Setting the Time: ■ Enter the menu by ►. HOUR blinks. ■ Press ▲ or ▼ to select the AM/PM (A. or P.) or 24H display mode (24H), which blinks. Validate by ►. HOUR ■ Press ▲ or ▼ to select the hour, which blinks. Validate by ►.

  • Page 22: Operation

    5. Operation 5.1. Inserting the Batteries amp and remove the instrument from any ■ Uncl connections and turn the rotary switch to the OFF position. ■ Use a Philips head screwdriver to unscrew the two attachment screws and remove the battery compartment cover.

  • Page 23: Display Example

    5.3. Display Example Figure 5-2 shows a typical display upon first use, with the device set to Ω+A. In this example the measured current is 30.0 mA and the impedan- ce is 7.9 Ω. The buzzer is active and the memory is empty. NOTE: This display corresponds to the device in Standard mode.

  • Page 24: Turning The Instrument On

    5.4. Turning the Instrument ON With the clamp closed and not clamped around any conductor, set the rotary switch to a position other than OFF. All icons on the display light for approxi- mately two seconds, before possible entry of the date and time (see § 5.2). During the first few seconds of operation, the clamp automatically adjusts cor- rection factors to optimize the impedance measurement.

  • Page 25: Standard And Advanced Modes

    5.8.1. Memory Capacity The EM5254 has a recording capacity of 2000 measurements. The PC interfa- ce can be used to activate a circular (first in/first out) recording mode in which the 2000 most recent values are kept, with a maximum sequence number of 9999.

  • Page 26: Reading Stored Data

    The display indicates the sequence number of the last measurement recor- ded, or 0 if the memory is empty. The data is preserved when the device is OFF or without a battery. 5.8.3. Reading Stored Data The data can be read using the MR function (see § 6.3). 5.8.4.

  • Page 27: Alarm Management

    5.9. Alarm Management The device has three distinct alarms that can be configured. NOTE: The (Ω, V, A) alarm thresholds can be configured in SET-UP (see §4.4). 5.9.1. Voltage Alarm ■ If the voltage (product ZxI) exceeds the threshold set, the alarm symbol and the alarm threshold blink.

  • Page 28: No Alarm Detection

    ■ Low Threshold Configuration: An audible signal is emitted when the impedance is below the threshold set (continuity type mea- surement). ■ High Threshold Configuration: An audible signal is emitted at values exceeding the threshold (detection of a grounding impedan- ce that is too high).

  • Page 29: Measurement Modes

    6. Measurement modes 6.1. Rotary position Ω +A 6.1.1. Standard Mode Selection of Standard mode is performed in the SET-UP (see § 4.4, menu #9). In Standard mode, only one measurement screen is available. The clamp me- asures the loop impedance (Ω) (at the fixed frequency of 2083 Hz) and the le- akage current.

  • Page 30: Measurement Results

    6.1.1.2. Measurement Results Once the measurement has stabilized, the display indicates: - The leakage current. - The impedance of the loop at the frequency of 2083 Hz. The impedance is measured only if the leakage current is less than 10 A. In the 10 to 40 A range, only the current is displayed;...

  • Page 31: Measurement Results

    6.1.2.2. Measurement Results First Screen: Once the measurement has stabilized, the display shows the first screen, which indicates: - The leakage current. - The loop impedance referenced to the chosen frequency. The impedance is measured only if the leakage current is less than 10A. In the 10 to 40 A range, only the current is displayed;...
  • Page 32 IIMPEDANCE GREATER THAN 1500 Ω In this case: - The impedance display indicates O.R (Over Range). Figura 6-6 LEAKAGE CURRENT DISTURBANCE If the current is greater than 5 A, or if it is signifi- cantly disturbed: - The blinking NOISE symbol is displayed. - The impedance blinks.

  • Page 33: Rotary Position (A)

    6.2. Rotary position (A) In the A position, the clamp measures the electrical current, independently of any ground/earth measurement. If desired, configure the current alarm threshold as desired (see §4.4, menu #6). 6.2.1. Making a measurement ■ Turn the rotary switch to the A position, and wait several seconds while the instrument performs internal calibration.

  • Page 34: Data Displayed In Advanced Mode

    The stored values are displayed as they were when recorded: same display range, alarm states, NOISE signal, battery condition, etc. However, the audible alarms are not reproduced; only the AL symbol and the alarm threshold blink. Figure 6-12 illustrates a current measurement (A setting).
  • Page 35 Third Screen: - Figure 6-16 illustrates a resistance and impedan- ce measurement (switch set to Ω+A). - Press ► to display the next screen. Figure 6-16 Fourth Screen: - Figure 6-17 illustrates the date and time of the measurement (switch set to Ω+A), namely: - 12.38: December 30 - 15:39: 1539 hours - Press ►...

  • Page 36: Especifications

    7. Especifications 7.1. Reference Conditions Reference Values Influencing Parameters Ambient temperature 73 °F ± 5 °F (23 °C ± 3 °C) Relative humidity 50% UR ± 10% Battery voltage 6 V ± 0.2 V < 40 A/m CC (no AC field) Magnetic field Electric field <...

  • Page 37: Loop Inductance Measurement

    Measurement Frequency: 2083 Hz Frequency Selection: Choice of 50, 60, 128, or 2083 Hz for the impedance calculation Maximum overloads: - permanent current 100 A maximum (50/60 Hz) - transient current (<5 s) 200 A (50/60 Hz) 7.2.2. Loop Inductance Measurement Measurement Range Resolution Accuracy...

  • Page 38: Power Supply

    7.2.5. Power Supply ■ 4 x 1.5 V LR6 (AA) alkaline batteries or 4 NiMH batteries ■ Battery Consumption: 140 mA approx ■ Battery Life: 12 hours, or 1440 30-second measurements approx NOTE: Extreme environmental conditions may interfere with the in- ternal microprocessor.

  • Page 39: Mechnical

    7.4. Mechnical Jaw Opening: 1.38" (35 mm) max Dimensions: 2.16 x 3.74 x 10.31" (55 x 95 x 262 mm) Weight: 2.06 lbs (935 g) approx. with batteries Environmental: IP40, group III equipment Drop Test: According to IEC-61010-1 7.5. Safety Electromagnetic Compatibility This instrument is compliant with standard IEC-61326-1.

  • Page 40: Maintenance

    ■ Never use alcohol, solvents or hydrocarbons. 8.2. Battery Replacement The EM5254 is powered by four 1.5 V batteries. The battery replacement indi- cator will blink when battery voltage is low and will display continuously when battery replacement is required.

  • Page 41: Additional Information

    (1) Wrist Strap. 10. Warranty MEGABRAS warrants the products for one year from date of shipment. We will repair, without charge, any defects due to faulty materials or work- manship. For warranty repair information, contact us or visit our webpage www.megabras.com.

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