How to Choose the Right ABB Contactor & Electrical Test Gear (A Buyer's Perspective)

There's No Universal 'Best' ABB Contactor Setup

If you're looking for a single answer on which ABB contactor to buy or how to test a coil without a multimeter, I'll save you some time: there isn't one. I've been managing electrical component purchasing for about five years now—processing roughly 60-80 orders annually across eight vendors for everything from contactors to test tools. The right choice depends entirely on your specific situation.

In my experience, buyers generally fall into three distinct scenarios. Once you figure out which one you're in, the decision becomes much clearer.

Scenario 1: You Need a Specific, High-Volume Contactor (Like the ABB AF80 or DP 40A)

This is the most common scenario I deal with. You have a clear spec—maybe you're replacing a failed unit on a production line or building a standard control panel. You know you need an ABB AF80 contactor or an ABB DP contactor 40 A.

What I've learned works

For standard, high-volume contactors, the key is vendor reliability, not price shopping. It's tempting to think you can just compare unit prices, but identical specs from different sources can result in wildly different outcomes. I once ordered a batch of AF09 contactors from a new supplier who was $4 cheaper per unit. They couldn't provide a proper invoice (handwritten receipt only). Finance rejected the expense report. I ate $240 out of the department budget.

Now, I prioritize vendors who:

• Carry ABB original stock (counterfeits are a real issue in this space)
• Provide clear, searchable wiring diagrams and catalogs
• Have a straightforward return policy for DOA (dead on arrival) units

(This approach worked for us, but we're a mid-size B2B company with predictable ordering patterns. If you're a seasonal business with demand spikes, the calculus might be different.)

Scenario 2: You Need an Integrated System (Like an ASCO Manual Transfer Switch + Contactor)

This is trickier. You're not just buying a single component; you're building a power management system. For example, you might be integrating an ASCO manual transfer switch with an ABB contactor for automatic load shedding or backup power control.

The trap to avoid

The biggest mistake I see is assuming all components are 'plug-and-play' together. The 'universal compatibility' advice ignores the nuance of coil voltage ratings, auxiliary contact configurations, and installation space. I've had projects delayed by weeks because a spec sheet didn't mention that a particular ASCO switch required a specific DC coil voltage not available on the standard ABB contactor we ordered.

If you're in this scenario:

1. Get the wiring diagram for the transfer switch first. This dictates everything else.
2. Match the coil type. ABB offers both AC and DC coils (e.g., AF series). An ASCO switch often uses DC control, so don't just grab the cheapest AC contactor.
3. Check the physical size. A large contactor like the AF80 might not fit inside a compact transfer switch enclosure.

(I can only speak to domestic installations using standard 600V gear. If you're dealing with high-voltage or international standards, there are probably factors I'm not aware of.)

Scenario 3: You're Troubleshooting and Need to Test the Coil (Without a Multimeter)

This is a classic 'how-to' question, often from a technician on-site who's lost their DMM or is working in a field environment. Seeing a keyword like how to test coil pack without multimeter tells me you're in a pinch.

The 'Stack Test' (It's not perfect, but it works in a pinch)

The simplest method is using an electrical safety tester (like a non-contact voltage tester) or a simple 9V battery.

1. Visual Check: Look for burn marks, cracks, or swollen plastic on the contactor coil. This is the first thing I do—it's free and often reveals the problem immediately.
2. The 'Stack Test': Take a small 9V battery (or a 12V battery, if you're sure of the coil voltage). Connect the battery's positive terminal to one coil lead and the negative to the other. A good coil will cause the contactor armature to pull in (you'll hear a 'click'). If it clicks, the coil is electrically intact.
3. The 'Sniff Test' (ugh, sorry): A burnt coil has a distinct acrid smell. If the contactor smells like burnt electronics, the coil is likely shorted.

Important caveat: This test only checks if the coil is electrically sound, not if it's mechanically jammed. The 'stack test' ignores the nuance of coil resistance. A coil that clicks with a 9V battery might still be failing under its rated voltage due to high resistance. For a definitive diagnosis, you really do need a multimeter to check the resistance (typically 50-500 ohms depending on the model) and compare it to the spec.

Looking back, I should have invested in a proper electrical safety tester sooner. I wasted an hour once trying to 'test' a coil with a flashlight battery. At the time, it seemed like a good idea because the multimeter was locked up. It wasn't. A simple NCVT (non-contact voltage tester) cost $15 and would have told me immediately if power was reaching the coil.

How to Tell Which Scenario You're In

If you're buying based on a clear spec (e.g., 'I need an ABB AF80, 110V coil'): You're in Scenario 1. Focus on vendor verification and avoid the price trap.

If you're integrating multiple components (e.g., 'I need a transfer switch and contactor to work together'): You're in Scenario 2. Your priority must be system compatibility, not component cost.

If you're on-site, troubleshooting, and don't have a multimeter (e.g., 'How can I test this coil?'): You're in Scenario 3. Use the 'Stack Test' as a quick check, but understand its limitations. Then buy a multimeter or an NCVT if you don't have one.

The best advice I can give is straightforward: know your scenario before you start looking. It prevents the frustration of buying the wrong part or misdiagnosing a problem. For us, embracing this approach has cut our troubleshooting time by a fair bit and eliminated those embarrassing moments of having to explain a failed test to a colleague.