Auto Mode

ATSE works on auto control mode normally. The controller monitors the real time values of both the sources. When there is source contingency, the transfer action will be energized to keep the power continuity for critical source.

Auto mode is supports U-G or U-U applications.

NOTE: Auto transfer will not be active, if transfer action damages driving system (for example, both sources are out of range, TSE refuses to transfer).

There are two types of auto control mode:

Auto-return
Non-return

Naming	Condition for stay on A situation return
Power source definition	N available A available	N available A unavailable
Auto-return	Switch to N	Switch to N
Non-return	Stay at A	Switch to N

Naming

Condition for stay on A situation return

Power source definition

N available

A available

N available

A unavailable

Auto-return

Switch to N

Non-return

Stay at A

Switch to N

Auto-Return

The auto-return has two modes as below:

When the voltage on the N source exceeds the threshold (overvoltage, undervoltage, over frequency, under frequency) or does not exist, the ATSE will be transferred to the A source.
When the voltage on the N source is within the threshold range, the ATSE will be transferred to N source.

The process of transfer can be controlled by time delay.

Transfer Process for Auto-Return U-U Application

Symbols	Description
Un	Source I
Ua	Source II
On	Contact close at N source
Oa	Contact close at A source
Load	Load status
T2	Transfer delay
T8	Loadshed delay
T4	Center-off delay
T6	Re-Transfer delay
Key O: OFF (circuit open) I: ON (circuit closed) : No power

Transfer Logic for Auto-Return U-U Application

T2 will reset if N becomes available or A becomes unavailable.

T2 will reset if N becomes unavailable
T6 Reset if N becomes unavailable
During T6, if A is not available it will keep to count T6 if the rest time of T6 is shorter than T2. Other wise it goes to T2
Retransfer principles when source A is ok, retransfer goes to T6 when source A is not ok and when source A is utility, retransfer goes to T2. If source A is Genset and not ok, retransfer delay is 0.

Transfer Process for U-G Application

Symbols	Description
Un	Source I
Ua	Source II
On	Contact close at N source
Oa	Contact close at A source
Load	Load status
T7	Genset start delay
T2	Transfer delay
T8	Loadshed delay
T4	Center-off delay
T6	Re-Transfer delay
T9	Genset cool delay
Key O: OFF (circuit open) I: ON (circuit closed) : No power

Transfer Logic for U-G Application

T2 will reset if N becomes unavailable
If disable Genset Start Fail Warning, T10 will not be counted
The whole transfer will be canceled if N becomes available during T7

T2 will reset if N becomes unavailable
T6 Reset if N becomes unavailable
During T6, if A is not available it will keep to count T6 if the rest time of T6 is shorter than T2. Other wise it goes to T2

Non-Return

In the non-return mode, after auto transfer to replacement, the ATSE will be connected to the alternate source until:

An external order is given to transfer back to N source.
The alternate source is out of range. In such case, the ATSE controller will transfer back to the N source to maintain power availability.

There will be only one time power off, when there is normal power outage.

Transfer Process of Non-return for U-U Application

Symbols	Description
Un	Source I
Ua	Source II
On	Contact close at N source
Oa	Contact close at A source
Load	Load status
T2	Transfer delay
T8	Loadshed delay
T4	Center-off delay
Key O: OFF (circuit open) I: ON (circuit closed) : No power

Logic of Non-return for U-U Application

T2 will reset if N becomes available or A becomes unavailable

T2 will reset if N becomes unavailable

Transfer Process of Non-return for U-G Application

Symbols	Description
Un	Source I
Ua	Source II
On	Contact close at N source
Oa	Contact close at A source
Load	Load status
T7	Genset start delay
T2	Transfer delay
T8	Loadshed delay
T4	Center-off delay
T9	Genset cool delay
Key O: OFF (circuit open) I: ON (circuit closed) : No power

Logic of Non-return for U-G Application

T2 will reset if N becomes available or A becomes unavailable
If disable Genset Start Fail Warning, T10 will not be counted

T2 will reset if N becomes unavailable