What ever happened to hand-cranks?

30 June 2015

The short answer? Nothing. They’re still here. Like Ford’s Model T is to automobiles, nothing more symbolizes the revolution in electrical testing and maintenance that began around the turn of the 20th century than the hand-cranked insulation tester. To this day, electricians and electrical maintenance personnel who at one time used this technology are still attracted when the remaining models are displayed at trade shows.

Unfortunately, the fond memories often include practical jokes. Fortunately for Megger, we kept ahead of this unwelcome tendency by relentlessly designing newer, safer models.

Introduced in the second half of the century, battery-powered insulation testers became the wave of the future. But with the technology not yet field-proven, some poorly designed instruments found their way onto the market, and promptly got a bad reputation in some circles, leaving old timers to rally around the hand-cranked generator.

Although battery-powered technology has now fully come of age and is thoroughly reliable, adherents to hand-cranked generators are still plentiful. Is there any basis for this? If we are talking about its use in the United States and why some are not willing to give them up, it is because of their reliability, the environment they are used in and an individual’s personal preference. If you ask any European, they are left scratching their heads wondering why with better and less expensive technology would anyone want to use something so antiquated. They are more amenable to starting from scratch.

No matter what can be said for the improved performance of batteries, the hand-crank tester’s one abiding weakness is that they eventually discharge. Spending an hour driving to a job site only to find that you have to drive back because the tester is dead and no one brought spares. This turns a routine job into an expensive and annoying project. The hand-crank, unless it’s literally broken (not easy to do; generators are quite rugged) is immune to ‘human error’. Environmental conditions can present unwelcome surprises. Batteries may not operate in extreme cold. Hand-cranked generators do.

On the other end, bright, sunny, hot days can wipe out the display that generally accompanies a battery-powered unit. Hand-cranks are typically mechanical analog operation, and you can always see the pointer!

Finally, and possibly most important, is purely user preference. Many operators have used these models from their apprenticeship and see no reason not to. No, a hand-crank does not provide a ‘better test’, although that is still a commonly held view. It may have been so when batteries were not always reliable, but not now. Veteran operators insist they can tell something about the test from the torque on the crank. This is not scientifically verifiable and cannot be promoted as a benefit. But, like the “handling” of a luxury car, if it works for you, it works. Depending on job demands, these benefits may be marginal, non-existent, or significant. But regardless, remember that time is money. If you may even remotely need to circumvent any of the problems listed above, having a hand-cranked insulation tester on the truck may quickly pay for itself.