14
S&C Instruction Sheet 659-555
Installation, Assembly, and Setup
Lugs for Battery and Power Connections
Use the following recommended lugs or equivalent:
• Panduit LCA4/0-12-X (COPPER)
• T&B CTL40L-12 (COPPER)
Metering Current Transformers
External metering current transformers (CTs) can be
connected at the terminal blocks located on the left side of
the cable termination area.
External CTs must be 5A output and the ratio is settable
in the HMI. The terminal blocks for the CTs are labeled CT
A, CT B, and CT C corresponding to each of the phases.
Earth Reference and Bonding
Earth Reference Requirements
A low-impedance earth reference connection is required for the
PureWave SMS-250 equipment. The earth (ground) reference
system should be tailored to reflect the characteristics of
the site and the requirements of the facility and shall use a
grounding interface that meets the needs of the local electric
utility’s system and that complies with all applicable national
and local electrical codes and standards. The PureWave
SMS-250 unit uses power converters that switch at frequencies
up to 5 kHz. For S&C PureWave SMS-250 equipment and
systems rated less than 1000 kVA, the resistance of the
PureWave SMS-250 earth reference connection to earth is
required to be 25 ohms or less at both the nominal power
frequency of 50 or 60 Hz and at the 5-kHz switching frequency
of the PureWave SMS-250 power conversion system.
Any associated battery equipment must have its own direct
earth reference connection. It is not permitted to only ground
the battery equipment through the PureWave SMS-250 earth
reference connections.
Bonding Requirements
Besides the importance of creating an earth reference, bonding
is required between interconnected electrical equipment to
establish a low impedance path that minimizes the potential
difference between two metallic objects, minimizes electric
shock hazards, provides lightning protection, and establishes
references for electronic signals.
All cable tray, conduit, and raceway systems installed to
interconnect power, control, and communications wiring to
and from the PureWave SMS-250 unit shall be electrically
continuous by bonding together at each individual section.
Each individual cable tray, conduit, and raceway section,
including pull boxes, junction boxes, and outlet boxes, shall
be bonded to the facility earthing system within 2 feet
(610 mm) of each end and at intervals not exceeding 50 feet
Figure 7. Example of a ground-plan diagram showing the S&C
PureWave SMS-250 cabinet, the SMS-250 autotransformer
option, and a battery system.
Figure 8. Example of a ground-plan diagram showing two S&C
PureWave SMS-250 cabinets and a pad-mount isolation trans-
former (var-only application—no battery system).
AUTO
TRANSFORMER
OPTION
BATTERY
SYSTEM
SMS-250
MINIMUM 72”
CLEARANCE
TO BATTERY
LEGEND
GROUND CONDUCTOR #4/0 AWG BARE 7
STRAND COPPER
10 FT. (3048 MM) CU CLAD STEEL,
5/8 (16 MM) INCH DIA
#1 AWG CU TO #4/0 AWG CU EXOTHERMIC
CONN. OR APPROVED LISTED SWAGE
CONNECTION
TERMINATION TO GROUND CONDUCTOR
(1 AWG MINIMUM) BARE COPPER, 10 MM
THREADED STUD, SINGLE HOLE, LISTED
SWAGE LUG
GROUND CONDUCTOR TO SMS-250
EQUIPMENT (#1 AWG MINIMUM) BARE 7
STRAND COPPER
GROUND CONDUCTOR #4/0 AWG BARE 7
STRAND COPPER
10 FT. (3048 MM) CU CLAD STEEL,
5/8 (16 MM) INCH DIA
NEMA TWO HOLE PAD OR GROUND CLAMP
TO #4/0 CU CONNECTOR
#4/0 AWG CU TO #4/0 AWG CU
EXOTHERMIC CONN. OR APPROVED
LISTED SWAGE CONNECTION
PAD MOUNT
TRANSFORMER
SMS-250
SMS-250
LEGEND
#1 AWG CU TO #4/0 AWG CU EXOTHERMIC
CONNECTION OR APPROVED LISTED
SWAGE CONNECTION
TERMINATION TO GROUND CONDUCTOR
(1 AWG MINIMUM) BARE COPPER, 10 MM
THREADED STUD, SINGLE HOLE, LISTED
SWAGE LUG
GROUND CONDUCTOR TO SMS-250
EQUIPMENT (#1 AWG MINIMUM) BARE 7
STRAND COPPER
(15 meters) along the run. All cable trays, conduits, and
raceways shall be securely bonded to all brackets, hangers,
and structural members to which they are attached. The
resistance of each bonding connection shall not exceed
5 milliohms. The total bonding resistance between the
PureWave SMS-250 cabinet and any battery cabinet/enclosure
shall be no more than 1 ohm.
