Phase Converter Shopping Guide?
A phase converter is a rotating machine, quite similar to a
motor. The machine converts single-phase utility power into 3-phase
electricity for use by 3-phase equipment. We use a phase converter
where 3-phase utility is unavailable, or when it is too expensive
for us to install. A properly sized and purposefully chosen phase
converter is an economical option that will operate any load as
well as the utility 3-phase will, and a high-quality phase
converter provides an ample lifespan.
The primary decision the consumer must make is the choice
between a rotary or a static phase converter. Rotary 3-phase
converters are the most reliable type of converter, and they are
the most flexible. They produce true 3-phase power, and thus they
operated any type of load or combination of motors.
Static 3-phase converters do not generate true 3-phase power,
and are very similar to an electric rope starter. Once the motor is
started, static converters cannot balance the load between the
three legs. Therefore, using a static phase converter, the motor is
never able to develop full horsepower. However, they are suitable
for heaters, rectifier loads and single motor, small horsepower
applications.
The benefit of the static 3-phase converter is that it starts
quickly, and it is substantially less expensive than a rotary phase
converter. Therefore, if for your application, the motor can run at
70% of nameplate horsepower, and you start it infrequently, a
static phase converter is a great choice. By infrequent, we mean
less than four starts per hour.
Customers must know that there are no industry standards that
apply to phase converters. This means a couple of things for the
consumer. One, the price between similar models can vary
drastically. Two, low quality phase converters are far more trouble
than they are worth. Make it a point to research phase converter
brands, and pay the premium, if necessary, in order to get a high
quality model of the type you require.
In addition, never compare phase converters solely on the
nameplate horsepower rating. Ask for the NEMA frame size, and then
compare phase converters of equal frame size. Marketing often
suggests that you can achieve similar/same output from a small
frame size. This is impossible, so keep that in mind, and ignore
the clever marketing.