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Subject to change without notice
B a s i c s o f p o w e r s u p p l i e s
4 Concept of the
HM7042-5
In this instrument the advantages of a SMPS, especially
high efficiency, and those of a linear regulator, e.g. high
quality regulation, are combined. A high power DC/DC
converter is used as a preregulator for the following linear
regulators, this reduces the high losses typical of purely
linear regulation. The HM 7042-5 has 3 independent and
isolated voltage sources. In addition to the standard mode
of operation as a triple output supply all outputs may be
series or parallel connected.
In series conncetion the maximum available current is
limited to 2 A. Paralleling the two 32 V outputs will yield 4
A at a maximum of 32 V. Please note that series as well as
parallel conncetion may influence some specifications valid
such as output impedance, noise, regulation.
4.1 Output power of the HM7042-5
The maximum combined output power is 155.5 W. The
HM7042-5 has a temperature-controlled fan the rpm of
which will increase with rising temperature. This will ensure
sufficient cooling under all normal operating conditions.
4.2 Switching the display on/off
All HM7042-5 power supplies feature a pushbutton which
turns the outputs ON/OFF while the supply remains func-
tioning. This allows to preset all voltages to their respective
desired values prior to turning the outputs on by depressing
OUTPUT .
Exceeding the Low Voltage Protection!
For the series connection of all output voltages, it is pos-
sible to exceed the low voltage protection of 42 V. Please
note that in this case any contact with live components
is life-threatening. It is assumed that only qualified and
trained personnel service the power supplies and the
connected loads.
5 Introduction to
the operation
5.1 First time operation
Please observe especially the following notes:
– The line voltage indicated on the rear panel corresponds
to the available line voltage, also, the correct fuses for
this line voltage are installed. The fuses are contained
in the line voltage connector housing.
– The connection to the mains is either by plugging into
a socket with safety ground terminal or via an isolation
transformer of protection class II.
– No visible damage to the instrument.
– No visible damage to the line cord.
– No loose parts floating around in the instrument.
5.2 Turning on the HM7042-5
After turning on all outputs will remain disabled, protecting
the loads. Prior to pressing OUPUT all output voltages
should be set to their desired values. Also, after turn-on the
instrument will be in the operating mode “Current limit“. The
maximum current available can be set by CURRENT
. The mode “Electronic fuse“ may be selected after turn-on,
but after each turn-off-on cycle “Current limit“ will be set.
C o n c e p t o f t h e H M 7 0 4 2 - 5
Summary of Contents for HM7042-5
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