station-type arresters be installed on the line side
of the supply transformers. For 480-volt systems,
surge protection is not generally warranted if the
station system is connected to the utility line
through a transformer which has adequate surge
protection on the high side. Each 480-volt
installation should be investigated, however, to
determine whether surge protection is required,
especially where excessive switching voltages may
occur or where the lightning incidence rate is high.
**************************************************************************
A three-pole capacitor unit, equipped with built-in discharge resistors and
using a non-polychlorinated biphenyl (PCB) insulating medium, shall be
provided in the main terminal box. Each pole shall be rated [0.5
microfarad and [2,400] [4,160] volts line-to-line] [1.0 microfarad and 650
volts line-to-line]. Removable bus links shall be provided for motor
testing. These links shall be treated to resist corrosion, shall be
designed to maintain a positive contact, and shall have low contact
2.2.2
Surge Arresters
**************************************************************************
NOTE: Arrester maximum continuous operating voltage
(MCOV) rating shall be 3,000 volts line-to-ground
for 2,400-volt systems and for effectively grounded
4,160-volt systems, 4,500 volts line-to-ground
operating voltage for ungrounded or
resistance-grounded 4,160-volt systems, or other
ratings as required. An effectively grounded system
is defined as one in which X0/X1 is positive and
less than 3 and R0/X1 must be positive and less than
1 for all system conditions at the point of
application of the surge arrestor.
**************************************************************************
Surge arresters of the station type with porcelain tops shall be provided
in the main terminal box. The arresters shall be of the metal-oxide type
rated [3,000] [4,500] [_____] volts maximum continuous operating voltage
(MCOV) line-to-ground. Removable bus links shall be provided for motor
testing. These links shall be treated to resist corrosion, shall be
designed to maintain a positive contact, and shall have low contact
2.2.3
Space Heater
If recommended by the surge protection manufacturer, a space heater of
adequate capacity and rated 120 volts shall be provided. Space heaters
shall have a maximum watt density of 20 watts per square inch.
2.3
MOTOR TERMINALS AND BOXES
2.3.1
Stator Terminal Box
Drip-proof
cast iron or steel conduit terminal boxes, treated as specified
for frames
in paragraph GENERAL REQUIREMENTS, shall be supplied for housing
the stator
lead connections [surge capacitors] [and surge arresters] and
shall have
adequate space to facilitate the installation and maintenance of
SECTION 16221A
Page 19
Previous Page
