31
EN
Instruction Manual
EL 9000 HP Series
Date: 05-31-2011
About the device
3.3 Scope of delivery
1 x Electronic load
1 x Printed instruction manual
1 x Mains cord
4. General
4.1 Prologue / Warning
This instruction manual and the device are intended to
be used by users who know about the principle of an
electronic load. The handling of the device should not
be left to persons who are unaware of the basic terms of
electrotechnology, because these are not described in
this manual. Inappropriate handling and non-observance
of the safety instructions may lead to a damage of the
device or loss of warranty!
4.2 Mains connection / Grounding
The unit is grounded with the mains cord. Thus the unit
may only be operated at a mains socket with grounding
contact. This must not be interrupted with an extension
cable without grounding wire!
4.3 Cooling
The air inlets on the front and the air outlets at the rear
have to be kept clean to ensure proper cooling. Take care
of at least 20cm distance (at the rear) to any surrounding
objects in order to guarantee unimpeded air flow.
Caution! Hot air can emerge from the air outlets!
4.4 Disassembly
Warning!
The unit must not be opened and repaired by
the user.
When opening the unit or removing parts from the inside
with tools there is risk of electric shock by dangerous
voltages. Open the unit only at your own risk and discon-
nect it from the mains before.
Any servicing or repair may only be carried out by trai-
ned personnel, which is instructed about the hazards of
electrical current.
4.5 Temperature shutdown / Ventilation
The device is equipped with temperature controlled fans
which are permanently running. At higher temperatures,
the RPM will increase and result in a certain noise de-
velopment.
In case of overheating the device is automatically swit-
ched offline (standby). After cooling down to the allowed
temperature range it is automatically switching online
again.
The error remains indicated in the display until it is ack-
nowledged by using the „Input on/off“ button or read out
by a remote command. An internal error buffer stores up
to three different alarms and is purged when read.
4.6 Dynamic characteristics and stability criteria
The electronic load is characterised by short rise and
fall times of the current, which are achieved by a high
bandwidth of the internal regulation circuit.
In case of testing sources with own regulation circuits at
the load, like for example power supplies, a regulation
instability may occur. This instability is caused if the com-
plete system (feeding source and electronic load) has too
little phase and gain margin at certain frequencies. 180°
phase shift at > 0dB amplification fulfills the condition
for an oscillation and results in instability. The same can
occur when using sources without own regulation circuit
(eg. batteries), if the connection cables are highly induc-
tive or inductive-capacitive.
The instability is not caused by a malfunction of the load,
but by the behaviour of the complete system. An impro-
vement of the phase and gain margin can solve this. In
practice, a capacity is directly connected to the DC input
of the load. Recommended is 1µF, for slower systems
some 100µF can be necessary.
4.7 Temperature characteristics
The high power version of the electronic loads is modi-
fied so it can provide full input power at higher ambient
temperatures before derating. Comparison chart:
The derating, if it occurs at all, is depending on the am-
bient temperature:
Summary of Contents for 33200246
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