Fluke 374 FC/375 FC/376 FC/902 FC Clamp Meter Calibration Manual

Introduction

⚠️ Warning: To prevent electric shock or personal injury, read the Safety Information before you use the Product.

This manual provides all the information necessary to perform basic maintenance and make calibration adjustments for the 374 FC/375 FC/376 FC and the 902 FC Clamp Meters (the Product). All figures show the 376 FC unless noted.

For complete operating instructions, refer to the 375 FC/375 FC/376 FC Users Manual and the 902 FC Users Manual.

Safety Information

A Warning identifies hazardous conditions and procedures that are dangerous to the user. A Caution identifies conditions and procedures that can cause damage to the Product or the equipment under test.

⚠️ Warning: To prevent possible electrical shock, fire, or personal injury:

• Carefully read all instructions.
• Read all safety information before you use the Product.
• Use the Product only as specified, or the protection supplied by the Product can be compromised.
• Do not use the Product around explosive gas, vapor, or in damp or wet environments.
• Do not use the Product if it operates incorrectly.
• Do not use the Product if it is altered or damaged.
• Disable the product if it is damaged.
• Prior to use, ensure the Product is clean, dry, and in good repair. Do not use the Product if it has been exposed to water, cleaning solutions, battery electrolyte leakage, or other contaminants that may have entered the enclosure. These contaminants can reduce or eliminate the protection provided by the Product against electric shock or arc explosion. Have the product dried, cleaned, or repaired as necessary to ensure continued safe operation.
• Use only correct measurement category (CAT), voltage, and amperage rated probes, test leads, and adapters for the measurement.
• Do not exceed the Measurement Category (CAT) rating of the lowest rated individual component of a Product, probe, or accessory.
• Comply with local and national safety codes. Use personal protective equipment (approved rubber gloves, face protection, and flame-resistant clothes) to prevent shock and arc blast injury where hazardous live conductors are exposed.
• Before each use, examine the Product. Look for cracks or missing pieces of the clamp housing or output cable insulation. Also look for loose or weakened components. Carefully examine the insulation around the jaws.
• Do not use test leads if they are damaged. Examine the test leads for damaged insulation and measure a known voltage.
• Do not touch voltages >30 V ac rms, 42 V ac peak, or 60 V dc.
• Do not measure current while the test leads are in the input jacks.
• Do not apply more than the rated voltage, between the terminals or between each terminal and earth ground.
• De-energize the circuit or wear personal protective equipment in compliance with local requirements before you apply or remove the Flexible Current Probe.
• Measure a known voltage first to make sure that the Product operates correctly.
• Limit operation to the specified measurement category, voltage, or amperage ratings.
• The battery door must be closed and locked before you operate the Product.
• Connect the common test lead before the live test lead and remove the live test lead before the common test lead.
• Remove all probes, test leads, and accessories before the battery door is opened.
• Keep fingers behind the finger guards on the probes.
• Hold the Product behind the tactile barrier.
• Replace the batteries when the low battery indicator shows to prevent incorrect measurements.

⚠️ Warning: Do not use the HOLD function to measure unknown potentials. When HOLD is turned on, the display does not change when a different potential is measured.

Disconnect power and discharge all high-voltage capacitors before you measure resistance, continuity, capacitance, or a diode junction.

Remove the input signals before you clean the Product.

Use only specified replacement parts.

When batteries are changed, ensure that the calibration seal in the battery compartment is not damaged. If damaged, the Product may not be safe to use. Return the Product to Fluke for replacement of the seal.

Do not use in CAT III or CAT IV environments without the protective cap of test probe. The protective cap decreases the exposed probe metal to <4mm. This decreases the possibility of arc flash from short circuits.

Do not place magnet inside Category IV panel. Place it outside the panel instead.

For safe operation and maintenance of the Product:

• Repair the Product before use if the battery leaks.
• Have an approved technician repair the Product.

⚠️ Caution: To prevent possible damage to the Product or to equipment under test:

• Use the correct terminals, function, and range for measurements.
• Clean the case and accessories with a damp cloth and mild detergent only. Do not use abrasives or solvents.

Note: The Measurement Category (CAT) and voltage rating of any combination of test probe, test probe accessory, current clamp accessory, and the Product is the LOWEST rating of any individual component.

Symbols used on the Product and in this manual are explained in Table 1.

The Product

374 FC/375 FC/376 FC and 902 FC Clamp Meters

Description of Figure 1: A Fluke 374/375/376 FC clamp meter is shown, highlighting the clamp jaws, display, rotary dial, buttons (HOLD, MIN/MAX, LOG), and the tactile barrier for finger safety. The model shown is the 376 FC.

⚠️ Warning: To prevent possible electrical shock, fire, or personal injury:

• When measuring current with the Jaw, keep fingers behind the Tactile Barrier.

Electrical Specifications

374 FC/375 FC/376 FC Electrical Specifications

AC Current via Jaw

AC Current via Flexible Current Probe

Description of Figure 2: Position Sensitivity diagram showing a cross-section of the clamp with the conductor positioned at different distances (A, B, C) from the center, indicating the corresponding error percentages for i2500-10 Flex and i2500-18 Flex probes.

Measurement uncertainty assumes centralized primary conductor at optimum position, no external electrical or magnetic field, and within operating temperature range.

DC Current

AC Voltage

DC Voltage

mV dc (375 FC and 376 FC)

Frequency via Jaw

Frequency via Flexible Current Probe

Resistance

Capacitance

902 FC Electrical Specifications

Mechanical Specifications

Environmental Specifications

Performance Tests

Performance tests verify that the Product operates within the published specifications. These tests should be performed periodically and after service or repair. If the Product fails any part of the verification test, repair, and/or calibration adjustments are required. Refer to the Calibration Adjustment section.

In this section, the Product is referred to as the UUT (unit under test). Use these verification performance tests to ensure the values indicated on the UUT correspond, as closely as possible, with the actual measurement values.

For each test:

1. Set the UUT to the appropriate function.
2. Connect the UUT to the Calibrator.
3. Set the Calibrator output.
4. Compare the results to Table 2. (Where X = not applicable.)

The test passes if the UUT reads between the upper and lower limit.

Table 2. Performance Tests

Table 2. Performance Tests (cont.)

Calibration Adjustment

Use the calibration procedures to adjust the Product so that the values shown on the Product correspond as closely as possible with the actual measured values. Table 3 lists the equipment required for the calibration adjustment.

Table 3. Required Equipment

Static Awareness

Semiconductors and integrated circuits can be damaged by electrostatic discharge during handling. This notice explains how to minimize damage to these components.

1. Understand the problem.
2. Learn the guidelines for proper handling.
3. Use the proper procedures, packaging, and bench techniques.

Follow these practices to minimize damage to static sensitive parts.

⚠️ Warning: To prevent electric shock or personal injury. De-energize the product and all active circuits before opening a product enclosure, touching or handling any PCBs or components.

Calibration Setup

To set up the Product for calibration:

1. Turn the Product over and use a flat-head screwdriver to remove the battery compartment screw. See Figure 3.
2. Remove the battery door.
3. Remove the batteries.

Description of Figure 3: Illustrates the steps to remove batteries: unscrewing the battery compartment, removing the door, and taking out the batteries.

4. Remove the calibration sticker.
5. Connect the Power Supply to the Product battery terminals.
6. Turn on the Product.
7. Use a small jumper to short the two pads together under the calibration sticker. See Figure 4.

Description of Figure 4: Shows the calibration activation process, depicting the bottom of the clamp meter with two pads that need to be shorted using a jumper.

To setup the current calibration see Figure 5.

Description of Figure 5: Illustrates the "Current Calibration Setup", showing the clamp meter connected to a Fluke 5522A Calibrator via test leads, with the calibrator displaying various functions and outputs.

For each calibration adjustment:

1. Turn the rotary knob to select the function.
2. Apply the required output from the source to the Product.
3. Wait until each applied output stabilizes.

On the 37x FC Products, push [confirm] to confirm the value and move to the next step in the Adjustment Procedure. When you have completed all the steps, push [HOLD] to save the data to NVRAM storage.

On the 902 FC Products, push [confirm] to confirm the value and move to the next step in the Adjustment Procedure. When you have completed all the steps, push [HOLD] to save the data to NVRAM storage.

To view the target calibration point, push [MIN/MAX].

When calibration is complete:

1. Remove the power supply.
2. Replace the batteries.
3. Replace the battery compartment door and tighten the battery compartment screw.

VAC Adjustment Procedure

VDC/mVDC Adjustment Procedure

Ohm/Cap Adjustment Procedure

AAC Adjustment Procedure (374 FC, 375 FC, 376 FC)

AAC Adjustment Procedure (902 FC)

ADC Adjustment Procedure (374 FC, 375 FC, 376 FC)

uADC Adjustment Procedure (902 FC)

ROGO Adjustment Procedure (374 FC, 375 FC, 376 FC)

Temperature Adjustment Procedure (902 FC)

902 FC Temperature Zero Procedure

After you do the temperature adjustment (See Temperature Adjustment Procedure (902 FC)), you must zero the temperature.

1. Insert the K-type thermocouple connector to attach the 5522A and the Product.
2. Turn off the Product and wait 20 minutes.
3. Turn on the Product.
4. Use a small probe to push the calibration button.
5. Turn the control knob to [select function].
6. Push [AC/DC] twice, until the LCD shows C-37.

Maintenance

This section contains basic maintenance procedures.

Clean the Product

⚠️ Caution: To prevent possible damage to the Product or to equipment under test, do not use abrasive cleaners. They will damage the case.

To clean the Product, use a cloth with a mild cleaning solution.

Battery Replacement

⚠️ Warning: To prevent possible electrical shock, fire, or personal injury, and to prevent incorrect measurements, replace the batteries when the low battery indicator shows.

Replacement Parts

Replacement parts and accessories are listed in Tables 4. To order parts and accessories, see How to Contact Fluke.

Table 4. Replacement Parts and Accessories