Delayed Transition Transfer Switching
Fig. 3: Four pole, Delayed-Transition
Transfer Switch rated 2000 amperes.
ASCO Delayed Transition Transfer Switches are designed
to provide transfer of loads between power sources with a
timed load disconnect position for an adjustable period of
time. Applications include older style variable frequency
drives, rectifier banks, and load management applications.
• Available 150 through 4000 amperes.
• Utilizes reliable, field proven solenoid operating
mechanisms.
• Mechanical interlocks to prevent direct connection of
both sources.
• Indicator light (16mm, industrial grade
type LED) for load disconnect position.
• Adjustable time delay for load disconnect position.
Closed-Transition Transfer Switching
ASCO Automatic Closed-Transition Transfer Switches feature
main contacts that overlap, permitting the transfer of electrical
loads without power interruption. The switch transfers in a
make-before-break mode if both sources are within acceptable
parameters. Control logic continuously monitors source
conditions and automatically determines whether the load
transfer should be open (conventional non-overlap mode) or
closed transition. Available 150 through 4000 amperes.
Closed-Transition Transfer within 5 electrical degrees is
achieved passively, without control of engine generator set.
Therefore, no additional control wire runs are required between
the ATS and engine generator set governor. Plus, protective
relaying may not be required under normal operation since
the contact overlap time is less than 100 milliseconds
(consult your local utility on protective relay requirements).
Failure to synchronize indication and extended parallel time
protection is built-in to all 7000 Series closed transition
controls to prevent abnormal operation.
Fig. 2: Four pole, Closed-Transition Transfer
Switch rated 1000 amperes in Type 1 enclosure.
Page 4
7000 Series Power Switching Solutions
ASCO