Average Reviews:
(More customer reviews)SUMMARY: sophisticated Soft Start circuitry makes it possible for the
manufacturer to install low-amp, low-voltage low-cost components and
still not blow them out, but it does so by shutting the inverter down so
often that it is not usable for me.
DETAILS:
This 1500W Vector VEC 050D inverter runs exactly as designed, but the
design impairs its utility for me."Soft Start" protects the inverter's
main components, the MOSFET chopper transistors, from getting fried by
sudden surges in current or voltage.This means that, with motors, the
inverter goes into protective shut down, then restarts, then shuts down
again, making it impossible to run the motor.Running several hundred
watts of unneeded incandescent lights at the same time calms the Soft
Start circuitry down, but I can't afford to waste the power.
BACKGROUND ON INDUCTORS:A motor, even the 4.2A (507 watt) blower motor
in my furnace, draws a lot of amps upon startup.
Besides startup amps, there is a voltage problem.The motor can throw
voltage spikes back at the inverter if, once running, you pull out the
plug (or, better yet, wiggle the plug in and out).This is because all
motors have iron cores with powerful magnetic fields and moving coils of
copper wire.They are inductive loads.
Transformers are also inductive loads, but are less troublesome because
the copper isn't moving.Within a single AC cycle or less (a 60th of
a second), the magnetic fields are established within a transformer, and
the situation is calm for both transformer (load) and inverter.In
motors, the spinning coils of copper cut lines of magnetic field.And,
as in a transformer, the magnetic field itself is rapidly changing when
you pull the plug.For both reasons -- copper cutting lines of force
and lines of force rapidly changing -- motors can generate large voltage
spikes when switched off.
So much for the voltage surge on "OFF".What about the amperage surge on "ON"?Inductors are coils of wire.They are short-circuits drawing lots of amps until the magnetic fields they work with get established. The two issues are related -- the magnetic field generates a "back-EMF" (back Electromotive Force, aka "voltage") to oppose current flow and prevent the startup surge from repeating.On turn-off, you see the back EMF in isolation.
Where do these spikes-on-turnoff go?When plugged into the house
wiring, the whole house and the world beyond it absorbs -- and cap --
the voltage spike. In an inverter, the chopper MOSFETs behind the plug
absorb the spike and die, often into a short-circuited condition which
then blows all the fuses back at the battery end of the device.
WHAT INVERTER MFRs DO
There are three ways to build a reliable inverter:
1. Use more expensive MOSFETS rated for higher amps and higher voltages.
$1 buys you 22 amps and 200 volts, barely higher than the 110VAC we
want.
$4 buys you 54 amps and 250 volts -- no death at
inductive load-turn-on, but voltage still too low
$10 buys you 54 amps and 600 volts -- almost blow-out proof.
2. Add surge suppression for voltage spikes using a) a zener diode,b)
the MOV (Metal Oxide Varistor) surge suppressors we all use in our
outlet strips and/or c) gas discharge surge suppressor tubes.Because
of their fast action, many designers combine the gas tube with either of
the other classes of solid-state devices.
3. Devise a Soft Start circuit and shut the MOSFETs down (puts them into
a high resistance state) before a high voltage arises and/or before a
high current can pass though them.
COMPLAINT:
The Vector VEC 050D 1500W inverter will not run a 1/4 HP motor rated
5.2A or my furnace blower motor which draws 4.2A.The inverter is rated for about 3 times the wattage of these motors, but it still cycles
on and off.The motor is pulsed and never runs smoothly at full speed.
My older inverter runs both motors fine, even though it is rated 800W,
nearly half of the Vector.I would rather have a solid, old-fashioned
inverter than a fancy Soft Start circuit, because the solid,
old-fashioned inverter runs all my appliances and the Soft Start
inverter does not.
WORKAROUND ISN'T WORKABLE
It is possible to get the Soft Start circuitry to get out of the way
(not begin to shut the inverter down) by running a 300 watt worklight as
well as either motor.This gives the inverter enough of a resistive
load (that does not spike in current consumption or voltage) that the
inductive load does not trigger the Soft Start circuit to shut down the
inverter or take other protective action that interferes with power
generation.
The thermal cooling and mechanical solidity of this inverter are very
good.It looks clean.The compact design would make repair more of a
pain than with a single-level, more open layout, but that doesn't
matter.You will probably be unable to burn yours out, and I am
returning mine.
Click Here to see more reviews about: Vector VEC050D 1,500 Watt D/C To A/C Power Inverter With Power Level Meter
Product Description:
BIG BUCKS OFF a Vector 1,500 - watt Power Inverter. Run your laptop, recharge your cell phone! This unit converts power from your vehicle's 12V DC battery into 110 / 120V AC household power. 3,000W peak / 1,500W continuous output; 3 grounded AC outlets; Soft Start Technology gradually and safely ramps up the output voltage; Automatic reset starts automatically if the inverter shuts down; Noise-free technology filters modified sine wave, which eliminates horizontal lines and static; Turbo cooling; Measures 10 3/4 x 7 1/2 x 3"h., weighs 8 1/2 lbs. Order Yours! Vector 1,500-watt Power Inverter
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