What happens if there is a bad input on the backup side and the primary then fails on an ECO422/D?

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The behavioral logic of the ECO422D is described in table 2-3 on page 2-8 of the ECO422D user manual (also shown below). One general rule of thumb is that the unit will NEVER automatically switch to a bad signal; it can only switch to a bad signal if told to do so by the user.

As shown on line 1 of the table below, if the backup is bad and the primary fails in normal operation mode then no switch will take place and the unit will remain passing through the primary signals.

Ln. #	Power	User Config Mode	Switch Button	Primary is…	Backup is…	Output (auto mode)	Output (manual mode)
1	On	Normal	No Switch	Bad	Bad	No Switch	No Switch
2	On	Normal	No Switch	Bad	Good	Backup	No Switch
3	On	Normal	No Switch	Good	Bad	Primary	No Switch
4	On	Normal	No Switch	Good	Good	No Switch	No Switch
5	On	Normal	Switch	Bad	Bad	Switch	Switch
6	On	Normal	Switch	Bad	Good	Backup	Backup
7	On	Normal	Switch	Good	Bad	Primary	Primary
8	On	Normal	Switch	Good	Good	Switch	Switch
9	On	Override	No Switch	Bad	Bad	No Switch	No Switch
10	On	Override	No Switch	Bad	Good	Backup	No Switch
11	On	Override	No Switch	Good	Bad	Primary	No Switch
12	On	Override	No Switch	Good	Good	No Switch	No Switch
13	On	Override	Switch	Bad	Bad	Switch	Switch
14	On	Override	Switch	Bad	Good	Backup	Switch
15	On	Override	Switch	Good	Bad	Primary	Switch
16	On	Override	Switch	Good	Good	Switch	Switch
17	Off	n/a	n/a	n/a	n/a	Primary	Primary

What happens if there is a bad input on the backup side and the primary then fails on an ECO422/D?

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