User manual

Page 33
EA Elektro-Automatik GmbH
Helmholtzstr. 31-37 • 41747 Viersen
Germany
Fon: +49 2162 / 3785-0
Fax: +49 2162 / 16230
www.elektroautomatik.de
[e-mail]
EL 9000 B HP Series
Principle view of the derating characteristics:
10°C 20°C 30°C 50°C
40°C
P
ϑ
Starting at around 30°C (86°F) ambient tempera-
ture, the derating will continuously step down the
available input power.
The temperature range of the device is rated up
to 50°C (122°F). Above that point, the system
could shut down because of overtemperature
(OT). However, due to the continuous derat-
ing that will happen, if at all, only above 80°C
(176°F).
3.2.5 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 band-
width 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 complete system (feeding source and electronic load) has too
littlephaseandgainmarginatcertainfrequencies.180°phaseshiftat>0dBamplicationfulls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 inductive or inductive-capacitive.
The instability is not caused by a malfunction of the load, but by the behaviour of the complete system. An improve-
ment of the phase and gain margin can solve this. In practice, a capacity is directly connected to the DC input of
theload.Thevaluetoachievetheexpectedresultisnotdenedandhastobefoundout.Werecommend:
80Vmodels:1000μF....4700μF
200Vmodels:100μF...470μF
360 V models: 68μF...220μF
500Vmodels:47μF...150μF
750Vmodels:22μF...100μF