Product specifications
1
How do I put the power supply in the
constant current mode?
The power supply cannot be “put”
into the constant current mode. The
output settings of the power sup-
ply combined with the ohmic value
of the particular load determine
whether or not the power supply
is in constant current.
ie: The power supply inherently
resides in the constant voltage
mode. If the output voltage were
set to 24 volts and a 6 Ω load were
placed across the output terminals,
Ohm’s Law would require that
4 amps would flow (24 V/6 Ω). This
presumes that the constant current
setting of the power supply were set
to a value greater than 4 amps; lets
say 5 amps. Now, if the 6 Ω load were
replaced by a 2 Ω load, Ohm’s Law
would suggest that 12 amps (24 V/
2 Ω) would flow. However, the power
supply is set to go into constant cur-
rent at 5 amps. Therefore, the actual
output voltage would be 10 volts
(2 Ω x 5 A). The power supply will
now remain in constant current for
values of load = 0 Ω ≤ R < 4.8 Ω. Once
the ohmic value of the load becomes
greater than 4.8 Ω (24 V/5 A), the
power supply will again revert to
constant voltage operation at the
value of 24 volts.
More detailed specifications at
www.agilent.com/find/power
122
Power Products
Applications Information
2
I have 208 VAC, 3φ phase power; can it be
used to operate a product requiring 208 V
single phase?
Yes, see below.
3
Why are the required Watts and
VA so different?
Watts is a scalar quantity which is
frequently used to measure system
efciency. It is the energy supplied
by the utility company over a given
period of time and is commonly
referred to as power. Except for heavy
industrial users, the utility company
only bills users for the watts consumed.
Watts are directly convertible into
mechanical work or BTUs (British
Thermal Units) of heat. Wasted power
is paid for a second time in terms
of additional loading on the user’s
air-conditioning system. Mathemati-
cally, it is a scalar quantity resulting
from the vector product of two vector
quantities (volts and amps). It is
NOT the simple algebraic product
of the rms volts times rms current.
VA on the other hand IS the scalar
quantity resulting from multiplying
the magnitudes (rms) of the vector
Earth
(Safety Ground)
N L
120 Volts (Typ) 208 Volts (Typ)
Rear of Instrument
Note: Connections are made
from phase to phase.
Instrument requires an
ac input voltage in the
window 191-250 VAC
C Phase
A Phase
B Phase
Assume V (nominal) = 208 Vac
208 V @ 8% low = 191 V
208 V @ 12% high = 233 V
(Instrument operates between 191 & 250 VAC)
instrument will not operate on a 120 VAC line
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Power Products Terms