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Fluke 1550C FC vs Fluke 1555 FC

Fluke 1550C FC vs

Which one to choose for electrical testing?: Fluke 1550C FC vs Fluke 1555 FC

Are you seeking a high-quality insulation tester to assess your electrical equipment’s insulation? Interested in finding the perfect insulation tester for your needs? Look no further.


In this post, we’ll compare two leading insulation testers: the Fluke 1550C FC 5 kV Insulation Tester Kit and the Fluke 1555 FC 10 kV Insulation Tester Kit. These kits are designed for accurate and reliable testing and offer user-friendly features and compatibility with the Fluke Connect wireless app.

We’ll discuss the importance of insulation testers, delve into the operation and benefits of Fluke insulation testers, and then dive into a detailed comparison of the two kits. From features and advantages to drawbacks and costs, we’ll help you make an informed choice based on your testing needs and budget.

Stay tuned to enhance your understanding of insulation testing, choose the right tester, and effectively use the Fluke Connect wireless app to streamline your testing process.

Why do you need insulation testers, and what are they?

Insulation testers are tools that gauge an electrical insulation’s resistance. The substance that keeps conductors apart from one another and the ground is known as electrical insulation. It shields people and equipment against electric shocks and fires by preventing electric currents from going where they shouldn’t.

Ohms () are the unit of measurement for insulation resistance, which expresses how well the insulation can thwart the flow of an electric current. The insulation improves with increasing resistance. But with time, aging, moisture, heat, dirt, vibration, and mechanical damage can all cause the insulation to deteriorate. As a result, there may be a greater chance of short circuits, leakage currents, and system failures.

Insulation testing can assist you in finding these issues before they result in major harm or mishaps. You can determine the resistance and assess the insulation’s condition by delivering a high voltage (often between 250 V and 10 kV) to the insulation and monitoring the resulting current.

Indicators of how well the insulation can recover from stress and maintain its charge include the polarization index (PI) and dielectric absorption ratio (DAR). For various electrical equipment types, including cables, transformers, motors, generators, switchgear, and more, insulation testing is advised.

It can assist you in maintaining compliance with safety regulations, saving money on maintenance, increasing productivity and dependability, and extending the useful life of your equipment.

How exactly do Fluke insulation testers function?

Fluke is a well-known producer of electrical testing equipment, and its products are used by experts worldwide. Fluke insulation testers are made to conduct precise and dependable insulation testing in various settings.

They offer many characteristics that make them simple, secure, and long-lasting. The test voltage is applied to the insulation by Fluke insulation testers, and the resulting current is then measured. The resistance value is then shown on a sizable digital/analog LCD panel.

They also do setup-free calculations for additional factors like DAR and PI. Depending on the model, they feature configurable test voltages in steps of 50 V or 100 V so that you may pick the right level for your equipment. Additionally, the protection system on Fluke insulation testers removes the impact of surface leakage current on high-resistance measurements.

The accuracy of the measurement can be impacted by surface leakage current, which is the current that runs over the surface of soiled or wet insulation. The guard system uses a third lead to isolate this current from the measuring circuit and bypass it.

The warning feature on Fluke insulation testers also informs you when line voltage is present on the apparatus being tested. The voltage from the power source or supply is known as line voltage. It could be harmful if more than 50 V AC or DC. The warning function provides a voltage reading of up to 600 V AC or DC for greater user safety.

Additionally, Fluke insulation testers contain memory space for 99 measurements, with a distinct label allocated to each site for quick recall. Additionally, you can use a USB connection or a wireless adaptor to send your data to a computer or a smartphone.

The Fluke Connect app lets you remotely configure tests, start and stop them, examine trending graphs in real-time on your phone, and easily prepare reports using pre-made templates.

Fluke insulation testers have a battery life of approximately 750 tests between charges. Heavy-quality leads and clips that can resist high voltages and currents are included. Additionally, they include soft travelling cases that shield them from moisture and dust.

How do the Fluke 1550C FC 5 kV Insulation Tester Kit and the Fluke 1555 FC 10 kV Insulation Tester Kit vary?

Their maximal test voltage is the primary distinction between these two kits. Digital insulation testing up to 5 kV can be done with the Fluke 1550C FC 5 kV Insulation Tester Kit and up to 10 kV with the Fluke 1555 FC 10 kV Insulation Tester Kit.

This indicates that they are appropriate for various equipment kinds that call for various degrees of insulation testing. Examples include testing motors rated below 1 kV at twice their rated voltage plus 1000 V, between 1 kV and 5 kV at twice their rated voltage, and above 5 kV at their rated voltage plus twice their rated winding-to-ground voltage, as per the IEEE 43-2000 standard for rotating machinery testing.

Therefore, use the Fluke 1550C FC 5 kV Insulation Tester Kit to test motors rated below 5 kV. However, you may use the Fluke 1555 Kit to test motors rated above 5 kV or other high-voltage apparatus, such as switchgear or cables that require insulation testing up to 10 kV.

The ramp function of these two kits is another distinction. Using the ramp function, you can apply test voltages in a linear ramp or dwell mode. Instead of employing predetermined test voltages, this can assist you in more quickly and precisely locating weak places in your insulation.

The Fluke 1550C FC 5 kV Insulation Tester Kit only offers set test voltages in 50 V stages from 250 V to 1000 V and in 100 V steps above 1000 V up to 5000 V; it does not include a ramp function. With the ramp feature, the Fluke 1555FC 10 kV Insulation Tester Kit, you may specify a start voltage from 250 V to 1000 V in 50 V stages and an end voltage from 500 V to 10 kV in 100 V steps.

A dwell duration of 0 seconds to 60 minutes and a ramp time of 1 second to 60 minutes can also be configured. Once at the end voltage, the tester will keep it there for the dwell time before applying test voltages in a linear ramp mode from the start to the end. During the ramp test, you can monitor the breakdown voltage (if any), the leakage current, and the resistance value.

Finding the weakest spot in your insulation, typically where the breakdown happens, may be done using the ramp function. When the insulation fails, a strong current might pass through it and cause damage or fire. You can locate the breakdown using the ramp function to observe how the resistance value changes as the test voltage rises. You can use this to find the problematic location and fix or replace it before it leads to more issues.

Fluke 1555 FC 10 kV Insulation Tester Kit

What are the advantages and disadvantages of every kit?

Both kits offer similar advantages, including:

They are precise and dependable with a CAT IV 600 V safety rating, a three-year warranty, and automatic DAR and PI calculation.

Large digital/analog LCD screens, configurable test voltages, warning features, memory storage, and data transfer capabilities make them simple to operate.They are compatible with the Fluke Connect wireless app, which enables remote configuration, test starting and stopping, real-time trend graph viewing on mobile devices, and simple report creation using pre-designed templates.

They have strong leads and clips, long-lasting batteries, and plush carrying cases.

They do, however, have some shortcomings, such as:

You can compare the Fluke 1550C FC 5 kV Insulation Tester Kit with the Fluke 1555 FC 10 kV Insulation Tester Kit based on price, technical specifications, key features, and more. They are large and hefty, measuring roughly 27 cm x 39 cm x 18 cm (11 in x 15 in x 7 in) and weighing about 7 kg (15 lb) each.

Each year, they need to be calibrated, which raises the expense of maintenance.

Which one ought you to pick?

Your budget and testing requirements will determine the answer. The Fluke 1550C FC 5 kV Insulation Tester Kit may be more cost-effective if you just need to test up to 5 kV. However, for greater versatility and coverage when testing up to 10 kV, you may wish to get the Fluke 1555 FC 10 kV Insulation Tester Kit.

Additionally, you should take into account the kind of equipment you are evaluating and use the necessary test voltages in accordance with manufacturer or industry standards. Additionally, you should routinely inspect your leads and clips for wear and breakage and replace them as necessary.


In conclusion, the post compared the Fluke 1550C FC 5 kV Insulation Tester Kit with the Fluke 1555 FC 10 kV Insulation Tester Kit. These testers offer precision, dependability, and ease of use, catering to various insulation testing needs. The deciding factors lie in testing requirements and budget. The Fluke 1550C FC kit suits up to 5 kV testing economically, while the Fluke 1555 FC kit provides versatility up to 10 kV. It’s vital to consider equipment type and adhere to standards. Regular maintenance of leads and clips is essential. For more information, visit official websites or consult Fluke sales professionals.

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