General

If the duration of the outage is less than the power supply filtering time, it has no effect on the program which continues to run normally. If this is not the case, the program is interrupted and power restoral processing is activated.

Filtering time:

PLC

Alternating Current

Direct Current

Premium

10ms

1ms

Atrium

30ms

-

Quantum

10ms

1ms

Illustration

The illustration shows the different types of power restoral detected by the system.

Operation

The table below describes the power outage processing phases.

Phase

Description

1

On power outage the system stores the application context and the time of outage.

2

It sets all the outputs in the fallback state (state defined in configuration).

3

On power restoral, the saved context is compared to the current one, which defines the type of startup to be performed:

  • if the application context has changed (i.e. loss of system context or new application), the PLC initializes the application: cold start,

  • if the application context is the same, the PLC carries out a restart without initialization of data: warm restart.

Power Outage on a Rack, Other than Rack 0

All the channels on this rack are seen as in error by the processor, but the other racks are not affected. The values of the inputs in error are no longer updated in the application memory and are reset to zero in a discrete input module, unless they have been forced, in which case they are maintained at the forcing value.

If the duration of the outage is less than the filtering time, it has no effect on the program which continues to run normally.