Power Regulation / Constant Power / Power Limiting; Alarm Conditions; Power Fail; Overtemperature - Elektro-Automatik PS 9000 2U Betriebsanleitung

PS 9000 2U Series
3.2.3

Power regulation / constant power / power limiting

Power regulation, also known as power limiting or constant power (CP), keeps the
DC output power of a power supply constant if the current flowing to the load in
relation to the output voltage and the resistance of load reaches the adjusted value
according to P = U * I resp. P = U² / R. The power limiting then regulates the output
current according to I = sqr(P / R), where R is the load's resistance.
Power limiting operates according to the auto-range principle such that at lower
output voltages higher current flows and vice versa in order to maintain constant
power within the range P
N
While the DC output is switched on and constant power mode is active, then the
condition "CP mode active" will be shown on the graphic display by the abbrevia-
tion CP, as well stored as status which can also be read as a status message via
digital interface.
3.2.4

Alarm conditions

This section only gives an overview about device alarms. What to do in case your device indi-
cates an alarm condition is described in section „3.5. Alarms and monitoring".
As a basic principle, all alarm conditions are signalled optically (Text + message in the display), acoustically (if
activated) and as a readable status via the digital interface. With any alarm occurring, the DC output of the device
is switched off. In addition, the alarms OT and OVP are reported as signals on the analogue interface.
3.2.4.1

Power Fail

Power Fail (PF) indicates an alarm condition which may have various causes:
• AC input voltage too high (mains overvoltage)
• AC input voltage too low (mains undervoltage, mains failure)
• Defect in the input circuit (PFC)
• Not all required AC input phases are connected (see „2.3.4. Connection to AC supply" for requirements)
Switching off the device by the mains switch can not be distinguished from a mains blackout
and thus the device will signalise a PF alarm every time the device is switched off. This can
be ignored.
3.2.4.2

Overtemperature

An overtemperature alarm (OT) can occur if an excess temperature inside the device causes to switch off the DC
output. This alarm condition is shown as the message "Alarm: OT" in the display. In addition, the condition will
be passed as a signal to the analog interface where it can also be read as an alarm code, as well as alarm code
which can be read via digital interface.
An OT alarm has a lower priority than an OV alarm (overvoltage). If an OV alarm occurs during
an OT alarm, then the message "OT" will be overwritten by "OV"
3.2.4.3

Overvoltage protection

An overvoltage alarm (OVP) will switch off the DC output and can occur if:
• the power supply itself, as a voltage source, generates an output voltage higher than set for the overvoltage
alarm limit (OVP, 0...110% U
voltage alarm limit
This function serves to warn the user of the power supply acoustically or optically that the device probably has
generated an excessive voltage which could damage the connected load application.
The device is not fitted with protection from external overvoltage.
3.2.4.4

Overcurrent protection

An overcurrent alarm (OCP) will switch off the DC output and can occur if:
• The output current in the DC output exceeds the adjusted OCP limit.
This function serves to protect the connected load application so that this is not overloaded and possibly damaged
due to an excessive current.
EA Elektro-Automatik GmbH
Page 40
Helmholtzstr. 31-33 • 41747 Viersen
Germany
(see diagram to the right)
) or the connected load somehow returns voltage higher than set for the over-
Nenn
Fon: +49 2162 / 3785-0
Fax: +49 2162 / 16230
www.elektroautomatik.de
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