ABB ATS022, Installation And Operating Instructions Manual

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1SDH000760R0002, L4106
Installation and operating instructions, ATS022
3. Description
Figure 3.2 Two transformer oncoming lines
In this case, the installation scenario is the following: ATS is connected to two power incoming lines.
Both lines are the secondary section of a medium-low voltage transformer or in any case, there are two
lines normally present. One of the two lines has more importance; it is normally used to supply the plant.
The second line is an emergency line; it is used in case of an emergency.
In standard conditions, the ATS022 monitors the normal line, analyzing whether the voltage, frequency,
and phase balance are correct. If one of these values is out of the set threshold, after a time delay TS the
ATS022 sends an opening command to the protection device on the normal line. If the emergency line
is OK, the closing command to the protection device on the emergency line is executed after a set time
delay (TCE). In the same way, the ATS022 will control the back-switching sequence when the normal line
will restart properly working:
If Line 1 (= the normal line) comes back, after the set time delay (TBS) the ATS022 sends an opening
command to the protection device on the emergency line and the closing command to the protection
device on the normal line is executed after a set time delay (TCN).
The switching sequence can be summarized in the following steps:
An anomaly occurs on the normal line
Delay time TS
Opening the protection device on the normal line
Delay time TCE
Closing the protection device on the emergency line
The back-switching sequence can be summarized in the following steps:
The normal line will restart properly working
Delay time TBS
Opening the protection device on the emergency line
Delay time TCN
Closing the protection device on the normal line
Many anomalies can occur during both sequences:
a) Tripping any of the two protection devices
The ATS022 is connected with the digital trip signalling contacts (DI4, DI5) of the two protection devices.
An active trip signal will lock the switching logic in ATS022.
The Alarm LED will be switched ON to indicate an active alarm (DO6 activated). To reset this condition,
the protection device must be reset by pushing the RESET key. After resetting the device the logic is
enabled (DO6 disactivated, Alarm LED is OFF).
KA00428
3.3.1 Two transformer incoming lines