Conditioned Power Center 9
2.4 Safety Interlocks This product incorporates a safety interlock circuit that functions as a
secondary means of protection for personnel. Protective side panels and
hazard warning labels provide primary protection. However, in the event one
or more side panels are removed from the product prior to being de-
energized, the safety interlock system will de-energize the power conditioner.
The circuit consists of two safety interlock switches (one per each side access
panel) located in the center of the top side frame of the power conditioner.
The switches operate as a normally open circuit connected to the shunt trip
coil of the input circuit breaker. See Figure A. Activating either of these safety
interlock switches causes a 24 VDC signal to energize the shunt trip coil of the breaker. The 24 VDC signal is
derived from a low voltage, fused tap on the transformer secondary. The shunt trip circuit also uses stored
energy from a capacitive circuit to ensure that the shunt trip mechanism will function even in the event of a power
outage. The safety interlock switches are shown on the general circuit diagram found in subs ection 10.1 of
Section 10 of this manual.
If the power conditioner shunt trips as a result of removing the side panels, hazard-
ous voltages will remain at the input voltage connection to the rear of the main cir-
cuit breaker. Entering the enclosure under these conditions is classified as a Type
4 task under SEMI S2-0200 guidelines. This can be changed to a Type 1 task by disconnecting power at
the source before entering the enclosure.
The rotary handle of the main breaker is equipped with a
hinged center insert clearly identified with an arrow. The
rotary handle of the main breaker must be in the horizontal
position to proceed. See Figure B. Depress the insert on
the arrow on the left hand side causing the insert to extend
on the right revealing a slot to accommodate a locking
device as shown in Figure C. The lockout/tagout feature is
designed to prevent personnel from accidentally energizing
the power conditioner while maintenance, service or repair
is being performed. With the lockout/tagout engaged, hazardous voltages are still present at the rear of the input
circuit breaker where input power feeds connect to the power conditioner. Entering the enclosure under these
circumstances is classified as a Type 4 Task under SEMI S2-0200. Entering the enclosure may be classified as
a Type 1 Task if power is disconnected from the power conditioner at the source.
Figure B Figure C
Section 2 - Safety
Figure A