Gu ide Form S pecifications
Breaker Protective Systems (Power+™ Trip Units)
1. Each circuit breaker shall be equipped with a protec-
tive trip unit system to protect against overloads, short
circuits (and ground faults! as specified in the following
subparagraphs. The protective trip unit shall consist of a
solid-state, microprocessor-based, programmer; tripping
means; current sensors; power supply and other devices
as required for proper operation.
2. As a minimum, the trip unit shall have the fol lowing fea
tures and functions:
a. The housing shall be a meta llic enclosure to protect
against magnetic interference, dust and other con
taminants.
b. The protective system shall have reliable program
mable controls with repetitive accuracy and precise
unit settings.
c. All current sensing shall employ true rms technol
ogy for detecting overloads, (short-time overcurrent
conditions and ground-fault conditions).
d. The trip unit shall be equipped with long-life lithium
batteries - with automatic time delay shut-off fea
tures - to provide observation of trip targets.*
e. U L 489 and UL 489-SB2 Listed, CSA Certified, I EC 947-
2 Certified, field-installable, i nterchangeable rating
plugs. It shall not be necessary to change or remove
the trip unit to change the trip rating. Rating plugs
shall contain rejection features to prevent installation
of a plug with an i ncorrect current sensor rating.
f. I ntegral test jack for connection of a battery pack or
test kit to the breaker.
g. (When specified) the ground-fault function shall
contain a memory circuit to integrate low-level arcing
fault currents with time to sum intermittent ground
fault current spikes.
h. A mechanism with provisions for sealing the rating
plug and trip unit to make the installation tamper-re
sistant.
i. The unit shall be dual-rated for both 50Hz and 60Hz
operation. Noise immunity shall meet the require
ments of ANSI Standard C3 7.90.2
j. The trip unit shall display trip targets for long-time,
short-time, instantaneous and ground fault*.
*With optional Target Module
112
3. The trip units for the main and tie breakers shall include
the following protective functions:
a. Adjustable long-time current settings.
b. Adjustable long-time delay with four time delay
bands.
c. Long-time pickup warning indicator*
d. Trip targets for overload, short circuit (when specified).
and ground fault (when specified).*
e. SELECT ONE OF THE FOLLOWING:
1) Adjustable instantaneous pickup.
2) Adjustable short-time pickup and delay, with three
delay bands, and switchable l2t ramp and
adjustable instantaneous pickup.
f. OPTIONAL: Adjustable g round-fault pick-up and time
delay, with three delay bands, and switchable l2t
ramp.
4. The trip units for feeder breakers shall include the follow
ing protective functions:
a. Adjustable long-time current settings.
b. Adjustable long-time delay with four time delay
bands.
c. Long-time pickup warning indicator.*
d. Trip targets for overload, short circuit (when specified).
and ground fault (when specified)
e. S ELECT ONE OF TH E FOLLOWI NG:
1) Adjustable instantaneous pickup.
2) Adjustable short-time pickup and delay, with three
delay bands, and switchable l2t ramp and
adjustable instantaneous pickup.
f. OPTIONAL: Adjustable ground-fault pickup and time
delay, with three delay bands, and switchable l2t
ramp.
5. Current sensors shall be mounted on the breaker frame
and shall use encapsulated construction to protect
against damage and moisture. (For g round-fault pro
tection of a four-wire power system, a fourth - neutral
current - sensor shall be mounted in the cable compart
ment , and shall be compatible with the phase overcur
rent sensors.)
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