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- What is Constant Current operation
and what does it do for me? ( Normal Operation )
Answer; In constant current operation as you adjust the current, voltage
has no effect on how the load handles the current. The load will always
try to draw the current that it is set for no mater what the voltage is doing.
- How can an electronic load work
at 0 Volts?
It can't and there is just
no such thing as working at 0 volts, you need voltage to produce current. Always
make sure that the load will start at the low voltage and work both in the positive
and negative direction. Some of our competitors loads require more
voltage to start and run, then they will work to a lower voltage. Executive
Engineering electronic loads will always work (sink current) at there low
voltage specification.
- How does Constant Power operation work?
Answer; As the voltage of the power source (UUT) unit under
test increases
the current that the Electronic Load draws decreases. This protects the
Electronic Load from having to much power put into it.
- What is Constant Resistance, and
how does it work?
Answer; As the voltage changes the current is adjusted so as to maintain
the same resistance at all times.
- What is Quasi-Constant
Power? ( Stand Alone Operation )
Answer; For the electronic loads we produce. The Electronic
Load starts up in constant resistance mode, and switches over to constant
current mode and allows the power foldback circuit to control how much
constant current the load is allowed to draw when in operation.
I.E. Once the current is set for a certain voltage the electronic
load will try to sink (dissipate) that amount of power for any voltage it
will see.
EXAMPLE; if you have a 5 Vdc power source at 2 amps you are dissipating
10 watts of power. If you change that voltage to the load and do not adjust
the electronic load it will still try to dissipate 10 Watts. If the first
supply is 5 Vdc at 2 amps, 10 watts and the new supply is 12 Vdc the load
will adjust it's current from about 2 amps to about 0.80 amps
to dissipate 10 watts.
Our Electronic Load can be adjusted from 0 - 125 / 0 - 300 Watts of power.
The quasi-power control circuit is broken up into three straight line parts
that follows the approximation of what a real constant power circuit would
do. I.E. Quasi-constant power.
This allows the Electronic Load to be operated
in a production type of environment with reduced problems in a burn-in type
operation.
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What is Start-up Mode or switch mode
point, and what benefits does it have?
Answer: When your power source is first turned on, in most cases, they
start at 0 volts and increase their voltage to a voltage regulation point.
At some point the source must provide current to the Electronic Load. This is
the voltage point where the Electronic Load turns on and starts drawing current
from the power source UUT.
- How does the Slew Rate effect my power source?
Answer; Most power sources have a current slew rate, the speed or rate
of change that current can be supplied and the voltage regulated. If an
Electronic Load turns on too fast (draws too much current to fast) some
power sources will go into current limit or the supply will shut down.
We have a preprogrammed slew rate that should fit most cases, or if you
need to shorten or lengthen it; you can add an external timing capacitor.
- What is Current Share, and how does
it work?
Answer; This allows your Electronic Load to share the current with
another or other Electronic Load of the same type. Usually allowing you
to control all the loads with one control device ( pot / resistor / D to A).
- What is Paralleling Electronic Loads, what
benefit does it have?
Answer; In some cases you many have two Electronic Loads, one a high
power or high current, and another lower power or lower current. In most cases
you can connect both Electronic Loads to the same source. You might want
to use the high power for a course adjust and the low power for a fine
adjust. Or two loads just to get more power from the power source (power
supply).
- How does Current Monitor work, and
what does it tell me?
Answer; The current from the power source flows into the Electronic
Load and is measured by the loads circuits, it is then changed into a voltage
and sent to the current monitor output pin.
- What is Dynamic Load Regulation?
Answer; This is the rate of change or slew rate that a power source
connected to an electronic load can change in voltage and have the electronic
load follow that rate of voltage change. If the output of a power supply has a lot of ripple you
want electronic load to be able to follow it.
- How do I measure Common Mode Noise & what is it.
Common mode noise is measured from the chassis ground to a power input
terminal. Each measurement is made separate (one power terminal at a time),
the return must be isolated from the ground to do this measurement. Note:
All switching power supplies generate common mode noise. If this noise
amplitude is high enough it can cause problems in measurements or operation of
other test equipment..
- What is reflected ripple.
The ripple and/or current that a switching power supplies pulls through
its input. Each time it switches a current pulse is sent to the input then
a reflected current is sent back through the input line. This works just
like a standing wave on a coax.
- What is a switching Electronic
Load?
Answer; Some electronic load companies make a load that operates
like a switching power supply, turning on and off power devices at a fast rate to control
the average current through the load. This can and does have bad side effects,
under some conditions it can cause the power source to over heat, blow-up, or just
be unstable.
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