FAQ: Megger Insulation Testers, Profile Projectors & Test Equipment Buying

I'm the office administrator for a 40-person company. I manage all our maintenance and lab equipment ordering—roughly $80k annually across 8 vendors. I report to both ops and finance (which means I get pulled in two directions regularly). When I took over purchasing in 2020, I knew test equipment existed. I didn't know I'd need to learn the difference between a Megger and a multimeter, or why anyone would spend $2k on a height gauge. So here's a FAQ for anyone in the same boat.

Common Questions on Megger Insulation Testers, Profile Projectors & More

What is the difference between a Megger and a standard insulation tester?

Honestly? Not much, these days. 'Megger' became a generic term (like Kleenex or Xerox). The company Megger produces a huge range of testers. When people search for 'Megger 210170 analogue insulation tester' or 'Megger MIT420/2 insulation tester', they are usually looking for a specific model for high-voltage tests.

The key difference in function: a standard multimeter checks for continuity and low resistance. An insulation tester, including the Megger brand, applies a high DC voltage (like 250V, 500V, or 1000V) to check if cable insulation is breaking down. That is their specialty. Don't use a $20 multimeter for this.

I'm not an electrical engineer, so I can't speak to the internal circuitry. What I can tell you from a procurement perspective is that if your maintenance team asks for 'a Megger', verify the voltage range they need. The MIT420/2 is a workhorse. The analogue 210170 is classic but less common now for new purchases.

Which Megger model should I buy: the 210170 analogue or the MIT420/2 digital?

This is the question that stumped me initially. The answer depends on who is using it.

The Megger 210170 is an analogue model. Some old-school electricians swear by the needle deflection because they claim it shows subtle trends in resistance drift that a digital display might mask. (Note to self: ask our senior electrician to validate this).

The Megger MIT420/2 is digital. It stores results, does PI and DAR ratios automatically, and is easier for our newer technicians to read. The risk: if a technician doesn't understand the settings, they can get a misleading result (ugh, I've seen that happen).

Our choice: we bought two MIT420/2 units for the team. The upside was data logging and easier calibration records. The risk was training. I kept asking myself: is saving $150 per unit on an analogue model worth potentially having inconsistent test results? The expected value said the digital was safer for our compliance audits.

What is a profile projector used for, and why does it cost so much?

A profile projector (also called an optical comparator) is used to magnify the silhouette of a small manufactured part—like a gear tooth or a screw thread—and measure it against a blueprint.

Why the high price? It's about precision optics and a large, shadow-free screen. You're paying for a heavy-duty optical bench. Cheap tabletop projectors exist, but they lack the lens quality for tight tolerances (like +/- 0.001 inch). When our QC department asked for one, I had to budget carefully. We ended up getting quotes from three vendors. The pricing varied by 40% for what looked like the same spec. We paid more for the vendor who provided a calibration certificate and a demo (best case: no surprises).

How do I choose a digital height gauge for inspection work?

This is fairly straightforward once you know the two specs to watch.

1. Range: Measure the tallest part you ever inspect. Add 25%. That is your minimum height gauge range.
2. Resolution vs. Accuracy: Don't confuse these. A cheap gauge might show 0.01mm resolution but have an accuracy of only +/- 0.03mm over the full range. For most workshop inspection, 0.01mm resolution is fine. For calibration labs, you need 0.001mm resolution. Verify this with the supplier.

Mitutoyo is the industry standard here. HIOKI and others make good ones. We bought a Mitutoyo for the toolroom because the reps offered a free training session (perspective: we needed it).

How often to change columns HPLC Agilent? (The one everyone is nervous about)

I am not a lab chemist, so I cannot speak to specific methods. But I manage the lab supply budget for two departments. We use Agilent instruments.

Take this with a grain of salt: column life depends 100% on sample cleanliness. According to our senior chemist, a good rule of thumb is:

• Clean analytes (pharma QC): 500-1000 injections per column.
• Dirty samples (environmental, food): 200-300 injections.
• If you see backpressure climb or peak shape degrade: Change it. Yesterday.

The cost of a column ($300-$700) is nothing compared to a failed batch run ($2,000 wasted). We use a column logbook. When we hit 80% of the expected life, we order a replacement. Simple.

What is the biggest mistake buyers make with test equipment?

Buying the cheapest option without checking calibration or repair costs. A $500 digital height gauge that costs $200 to calibrate (annually) and is unrepairable after 2 years is actually a $700 gauge over its life. A $900 gauge from a major brand that lasts 10 years and costs $100 to calibrate is cheaper overall. I've made this mistake. I bought a 'budget' pH meter for the lab. The electrode died in 6 months, and the replacement was almost as much as a new one from a proper brand. I ate that cost. Now I ask about spare parts and calibration costs before I order any instrument. I'd rather spend 15 minutes explaining why we buy Fluke or Megger than deal with a broken budget tool during a critical shutdown.