2,300- and 4000-volt motors, surge capacitors and
arresters, mounted at the motor terminals, should be
specified. In addition, it is recommended that
station-type arresters be installed on the line side
of the supply transformers.
**************************************************************************
2.6.1
Surge Capacitors
A three-pole capacitor unit, equipped with built-in discharge resistors and
using a non-polychlorinated biphenyl (non-PCB) insulating medium, shall be
furnished and installed in the main terminal box. Each pole shall be rated
0.5 microfarad and [2,400] [4,160] 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 resistance.
2.6.2
Surge Arresters
**************************************************************************
NOTE: Use 3,000 MCOV arresters for 2,400-volt
systems or effectively grounded 4,160-volt systems.
Use 4,500-MCOV for ungrounded or resistance grounded
4,160-volt systems.
**************************************************************************
Surge arresters of the station type with porcelain tops shall be furnished
and installed in the main terminal box. The arresters shall be of the
metal-oxide type rated [3,000] [4,500] [_____] maximum continuous operating
voltage 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
resistance.
2.6.3
Space Heater
If recommended by the surge protection manufacturer, a space heater of
adequate capacity and rated 120 volts shall be furnished and installed in
the terminal box. Space heater maximum watt density shall not exceed 20
watts per square inch.
2.7
CURRENT TRANSFORMERS
**************************************************************************
NOTE: For motor differential protection, the
"Flux-Balancing Current Differential" scheme, as
shown in Fig. 16 of IEEE C37.96, is preferred and
will generally be applicable. In this case, the
window-type current transformers should be used.
However, when the KVA rating of a motor is
approximately one-half the supply transformer KVA
rating, or greater, it may be necessary to use the
differential scheme shown in Fig. 15 of IEEE C37.96,
in which case the "Differential Protection" scheme
should be used.
**************************************************************************
Current transformer shall meet the applicable requirements of IEEE C57.13
and IEEE C37.96. Secondary circuits [shall] [shall not] be grounded at the
SECTION 16222A
Page 24
Previous Page
