Cooper Lighting 84700 - Manual (Page 10)

9131
Rev. M
SECTION 2
TECHNICAL DESCRIPTION
2.1 THEORY OF OPERATION
The operational discussion presented herein pertains to standard model CSC units.
Equipment supplied with options may deviate somewhat from the exact operational
description presented, but the basic operating principles are identical for all
equipment configurations.
2.1.1 Local Control
The CSC control circuits operate from the 120 VAC primary power source and
energize the relay coils in the high voltage circuit to supply power to the lighting
circuit selected. When switch, remote-off-local, is selected to LOCAL, switches S1
and S2 (S1 through S4) are active. When any of these switches is set to ON, a signal
is applied to the timing circuits located on the circuit card assembly. The timing
circuit, in turn, supplies power immediately to the coil of the respective double pole
relay in the high voltage section. After a brief delay, less than one second, the timing
circuit supplies power to the coil of the associated single pole shorting relay in the
high voltage section, thus energizing the lighting circuit. (Note: Due to the
characteristics of Type L-828 Regulators, the other lighting loads may dim
momentarily. This is normal.) To de-energize a lighting circuit, the respective
control switch is selected to OFF. This action immediately de-energizes the single
pole shorting relay, which places a short across the lighting circuit. After a brief
delay, the timing circuit removes power from the coil of the double-pole isolating
relay, which opens to isolate the lighting circuit from the regulator. The timing
diagram in Figure 2-1 may be helpful in understanding the switching sequence.
De-energized switching (Option -1) is installed on all units. This turns the regulator
off prior to switching the circuits and turns the regulator back on after the circuits
have been switched. See Sections 3.1.3.2 and 3.1.4 for more detail.
2.1.2 Remote Operation
The CSC, when operated remotely, functions exactly the same as when under local
control, except that switches S1 and S2 (S1 through S4) are not active. Remote
control power is normally derived internal to the CSC. However, external power
sources may be used if the proper option is specified.
2.1.3 CCR Interlock
An interlock switch is provided for the high voltage section of the CSC. This switch
should be connected in series with the control circuit of the CCR to provide for
immediate shutdown of the CCR in the event that the dead front cover of the CSC is
removed. Normally, however, the CCR or CCRs should be de-energized prior to
removal of the dead front cover
4