Hameg Instruments HM7042-5 Manuel page 22

B a s i c s o f p o w e r s u p p l i e s
In order to increase the total available current the outputs of
supplies can be paralleled. The output voltages of the supplies
involved are adjusted as accurately as possible to the same
value. In this mode it is possible that one or more supplies
enter the current limit mode. The output voltage remains in
regulation as long as still at least one supply is in the voltage
control mode. It is recommended but not absolutely necessary
to fine adjust the voltages such that the individual current
contributions remain nearly equal. Of course, the maximum
available output current is the sum of the individual supplies'
maximum currents.
Example: Example: Example: Example: Example:
A load requires 12 V at 2.7 A. Each 32 V output of the HM 7042-
5 can deliver 2 A. First set both supplies to 12 V. Then connect
both black and both red safety connectors respectively in pa-
rallel. The load is connected to one of the supplies. With the
pushbutton OUTPUT “ the voltage will be turned on. It is nor-
mal that one output will current limit at 2 A while the other
will contribute the balance of 0.7 A in voltage regulation.
In case you should parallel power supplies of other
manufacturers with HAMEG supplies make sure all
are specified for this mode of operation. If one
supply of those connected in parallel should have
STOP STOP
insufficient overload protection it may be
destroyed. HAMEG supplies are specified for
series and parallel operation.
Current limit
means that a maximum current can be set. This is e.g. useful
in order to protect a sensitive test circuit. In case of an
inadvertent short in the test circuit the current will be limited
to the value set which will in most cases prevent damage.
U
out
U
const
Adjustment of current
The picture shows that the output voltage V
while the current I increases until the current limit selected
will be reached. At this moment the instrument will change
from constant voltage regulation to constant current regu-
lation. Any further load increase will cause the current to
remain stable while the voltage decreases ultimately to zero.
Electronic fuse
In order to provide a still better protection than current limiting
offers the HM 7042-5 features an electronic fuse. As soon as
I is reached all outputs will be immediately simultaneously
max
disabled.
They may be turned on again by depressing OUPUT “.
22
Sous réserve de modifications
All manuals and user guides at all-guides.com
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.
Output power of the HM 7042-5
The maximum combined output power is 155.5 W. The
HM 7042-5 has a temperature-controlled fan the rpm of which
will increase with rising temperature. This will ensure
sufficient cooling under all normal operating conditions.
Switching the display on/off
All Hameg supplies feature a pushbutton which turns the
outputs ON/OFF while the supply remains functioning. This
allows to preset all voltages to their respective desired values
prior to turning the outputs on by depressing OUTPUT “.
I
I
max
out
–
remains stable,
out
–
–
–
–
Turning on the HM 7042-5
After turning on all outputs will remain disabled, protecting
the loads. Prior to pressing OUPUT ➇ 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
on, but after each turn-off-on cycle "Current limit" will be set.
Concept of the HM7042-5
Exceeding the safety voltage level of 42 V!
If all outputs are series connected the maximum
output voltage can exceed 42 V. In such case
touching of live parts may be fatal! Only qualified
and well instructed personnel is allowed to use
such installations!
Introduction to the operation
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.
. The mode "Electronic fuse" may be selected after turn-