Cutler-Hammer ATVISPE31000XSU, Instructions Manual

Page: 27 / 44

I.B. ATS-SD02
Page 21
Effective 5/98
SECTION 5: OPERATION
5.1 GENERAL
A transfer switch provides main contacts to connect and
disconnect the load to and from the normal and emer-
gency power sources (Paragraph 3.2.1). A stored-energy
type transfer mechanism provides the mechanical motion
required to open and close the mechanically interlocked
main contacts (Paragraph 3.2.4 and Figure 3-2).
Each switch can be manually operated. Before a switch-
ing device can be closed, the stored energy mechanism
must be charged by pumping the handle (Figure 5-1).
The switching device can be closed by pushing the
close button (Figure 5-2). The other switching device is
prevented from closing through a rigid mechanical inter-
lock (Paragraph 3.2.2). An indicator window shows
whether the switch is open or closed.
If a transfer switch with any type of electrical operat-
ing capabilities is to be operated manually utilizing
the manual operating handle, it is strongly recom-
mended that the transfer control circuit first be iso-
lated. This is accomplished by disconnecting the
logic panel. If, however, a transfer switch is sup-
plied with a four-position selector switch (Option
6H), it can be turned to the off position, making it
unnecessary to unplug the logic. In the case of the
automatic transfer switch design, any attempt to
operate the manual handle without first isolating the
control circuit causes an automatic transfer.
5.2 AUTOMATIC TRANSFER SWITCH
The operating sequence of an automatic transfer switch
is dictated by the switch’s standard features and select-
ed options. Operation of an automatic transfer switch
during normal power source failure and normal power
source restoration will be described here with only stan-
dard options included on the switch. Additional options,
as described in Section 3 or in separate instruction doc-
uments, can change sequences and timing depending
upon the options selected. Become familiar with any
additional options selected and their effect on the nor-
mal operation of an automatic transfer switch.
Normal Power Source Failure
Standard normal power source failure is defined as a
reduction or loss of voltage. If this occurs, the sequence
of operation is as follows:
·
Failure of the normal power source is detected by
the logic.
·
When the intelligence circuit detects a failure, the
normal relay drops out, opening certain contacts
while closing others. One of the contacts starts the
engine-driven generator.
·
When the emergency power source voltage reaches
its operation rating, an emergency relay closes,
starting the transfer operation. This operating
sequence opens the normal switching device and
closes the emergency switching device.
·
The load is now transferred to emergency power
source.
Figure 5-1 Pumping Handle Charges Stored Energy
Mechanism Figure 5-2 Close Switch by Pushing Close Button
NOTICE