4 Using the Photovoltaic Array Simulator
Fault/Inhibit System Protection
As shown in the following figure, when the Fault outputs and Inhibit inputs of several instruments are
daisy-chained, an internal fault condition in one of the units will disable all outputs without
intervention by either the controller or external circuitry. Note that when using the Fault/Inhibit signals
in this manner, both signals must be set to the same polarity.
Also, as shown in the figure, you can also connect the Inhibit input to a manual switch or external
control signal that will short the Inhibit pin to common whenever it is necessary to disable all outputs.
Negative polarity must be programmed for all pins in this case. You can also use the Fault output to
drive an external relay circuit or signal other devices whenever a protection fault occurs.
Clearing a System Protection Fault
To restore all instruments to a normal operating condition when a fault condition occurs in a daisy-
chained system protection configuration, two fault conditions must be removed:
1. The initial protection fault or external Inhibit signal.
2. The subsequent daisy-chained fault signal (which is sourced by the Inhibit signal).
Even when the initial fault condition or external signal is removed, the fault signal is
still active and will continue to shut down the outputs of all the units.
To clear the daisy-chained fault signal if the operating mode of the Inhibit input is Live, simply clear the
output protection on any ONE unit as explained under
mode of the Inhibit input is Latched, turn off the Inhibit input on ALL units individually. To re-enable the
chain, re-program the Inhibit input on each unit to Latched mode.
Output Couple Control
This function lets you connect multiple instruments together and synchronize the output on/off
sequence across all units. Each unit that will be sequenced must also be "coupled" to the other units.
1. Couple the output on each unit as described under
2. Set the delay offset of each individual unit to match the longest delay offset of the group.
3. Connect and configure the digital connector pins of the sequenced units as shown below.
154
Clearing Protection
Sequencing the
Output.
Keysight PV8900 Series Operating and Service Guide
Functions. If the operating