Instructions

Page 67
EA Elektro-Automatik GmbH
Helmholtzstr. 31-37 • 41747 Viersen
Germany
Fon: +49 2162 / 3785-0
Fax: +49 2162 / 16230
www.elektroautomatik.de
[e-mail]
PS 9000 3U Series
3.9.4.3 Settings on the devices
The master-slave settings in the MENU of the load device(s) also a󰀨ect the Share bus. For correct 2QO operation,
all involved load units must be slaves on the Share bus. This is achieved by setting the master-slave mode to
OFF or SLAVE, depending on if there is digital master-slave in use or not. For the one load that is master (setting:
MASTER) in the master-slave system the additional parameter “PSI/ELR system” resp. “PSI/EL system” has to
be activated.
On any of the power supplies, you need set parameter “Share bus mode” to MASTER. Also see 3.4.3.1.
For safety of the connected E.U.T / D.U.T and to prevent damage, we recommend to adjust supervision thresholds
like OVP, OCP or OPP on all units to the desired levels, which will then switch o󰀨 the DC output resp. the DC input
in case of excess.
3.9.4.4 Restrictions
After all electronic loads have been connected to the Sharebus with one power supply as master, they can’t limit
their input voltage anymore to what you adjust as “U set” on the device. The correct voltage level comes from the
2QO master unit (power supply) and has to be adjusted there.
If the applications requires to use the remote sensing feature in order to achieve a higher voltage accuracy on the
E.U.T. only the master must be wired its Sense connector.
Using the Sense input must be considered with caution, because it could increase the tendency
of oscillation.
3.9.4.5 Application example
Charging and discharging a battery with 24 V / 400 Ah, using conguration A from above.
• Power supply PS 9080-170 3U with: I
Set
= 40 A (charging current, 1/10 of capacity), P
Set
= 5000 W
• Electronic load ELR 9080-170 set to: I
Set
= max. discharging current of the battery (eg. 100 A), P
Set
= 3500 W,
plus probably UVD = 20 V with event type “Alarm” to stop discharging at a certain low voltage threshold
• Assumption: battery has a voltage of 26 V at test start
• DC input(s) and DC output(s) of all units switched o󰀨
In this combination of devices it is recommended to always switch on the DC output of the
source rst and then the DC input of the sink.
1. Discharge of the battery to 24 V
Setup: Voltage on the power supply set to 24 V, DC output of power supply and DC input of load activated
Reaction: the e-load will load the battery with a maximum current of 40 A in order to discharge it to 24 V. The power
supply delivers no current at this moment, because the battery voltage is still higher than what is adjusted on the
power supply. The load will gradually reduce the input current in order to maintain the battery voltage at 24 V. Once
the battery voltage has reached 24 V with a discharge current of approx. 0 A, the voltage will be maintained at this
level by charging from the power supply.
The power supply determines the voltage setting of the load via the Share bus. In order to avoid
deep discharge of the battery due to accidentally setting the voltage on the power to a very low
value, it is recommended to congure the undervoltage detection feature (UVD) of the load, so
it will switch o the DC input when reaching the discharge voltage. The settings of the load, as
given via the Share bus, can’t be read from the load’s display.
2. Charging the battery to 27 V
Setup: Voltage on the power supply set to 27 V
Reaction: the power supply will charge the battery with a maximum current of 40 A, which will gradually reduce
with increasing voltage as a reaction to the changing internal resistance of the battery. The load absorbs no current
at this charging phase, because it is controlled via the Share bus and set to a certain voltage, which is still higher
than the actual battery voltage and the actual output voltage of the power supply. When reaching 27 V, the power
supply will deliver only the current needed to maintain the battery voltage.