POWER SUPPLY INFORMATION
DC power supplies from the manufacturers are available in many different sizes and
total power (watts) from the single 3 Volt @ 2 Amps maximum to the dual 50 Volt @
20 Amps maximum unit.
The method of calculation the maxim watts that a power supply
can provide is to multiply the maximum volts by the maximum amps that are available.
For example the Mastech HY3020D has a rating of 30 volts and 20 amps maximum so 30
times 20 equal 600 watts potential.
It is not recommended to exceed
80% of the maximum rated watts usage.
Always purchase a more powerful supply than
your minimum requirements to allow for future growth and for out of spec devices.
All of the dc power supplies that are being discussed are variable both for volts
and for watts but there is a difference in the absolute voltage control and the maximum
amps control. When a given voltage is dialed in on the display (say 24 volts) the
power supply will give exactly (+/- 2% accuracy on most units) that much voltage
to the unit that will be powered.
On the other hand the amps control works differently because the power supply can
not be forced to provide more amps than the hooked up device requires. If a particular
device needs 7 amps the power supply will not give it more even if the amp control
is set at maximum (10 amps for the Mastech HY3010E). Once the hooked up equipment
is running the exact amp level that is being used will be displayed on the meter
(+/- 2% accuracy on most units). You can lower the amps that are provided and the
corresponding new level will be displayed but you can’t increase the level that it
will draw.
There are two primary design types available. On is the traditional LINEAR design
and the other is a newer SWITCHING design.
The LINEAR models will work for any application
as long as the maximum power is not used on a continuous basis. The switching models
are best for radios, RC cars and trains and other non sensitive electronic equipment.
They are not recommended for plating or ionizing.
The benefits of the LINEAR power supply is that they are heavy duty units that can
handle continuous use and produce very low line noise that can effect sensitive equipment.
There design of using large DC transformers, heat sinks and fans causes them to be
heavier and more costly than their switching power supplies. Be careful when reading
the details in an ad as some can be misleading regarding if they are linear or not.
A 0-30 volt @ 0-5 amp dual linear power supply typically weighs between 30 and 35
pounds so a 15 pound unit will be a switching type even if the ad’s description states
linear.
The main benefits of a SWITCHING power supply are that they are much lighter and
less costly over their switching counterparts. For example the Mastech HY3020D linear
power supply weighs 41 pounds while the Mastech HY3020E switching power supply weighs
less than 17 pounds.
Their display screens can come in many varieties: backlit LCD meters, red LED meters,
green LED meters and the newest dual color LED meters such as the Mastech HY3005F-3
which has red and green LED meters.
Many of these power supplies come in DUAL VARIABLE configurations which mean the
supply has two independent supplies within the cabinet and they can be used in INDEPENDENT,
SERIES or PARALLEL operation which can provide either dual 0-30V @ 0-5A or one 0-60V
@ 0-5A or one 0-30V @ 0-10A connection for the Mastech HY3005D-3 for example. Dual
supplies have -2 after their model numbers.
Triple power supplies provide dual variable
and a third FIXED output which is usually 5 volts at 3 amps.
One important deciding factor that you should use after selecting a Mastech power
supply for purchase on the Internet is to find out if the seller has a technician
available. Most sellers do not and if something goes wrong with your supply during
the warranty period there could be a delay in replacing it if the seller is out of
stock. Stock levels fluctuate and many times out of stock conditions occur and the
next replacement container ship could be months away.
