Emerson K675A Technical Specifications

ENGINEERING SPECIFICATION

FOR HORIZONTAL AIRFLOW

OUTDOOR RESISTIVE LOAD BANK

(200-500 KW)

PART 1.0 GENERAL

1.1 SCOPE

A. This specification contains the minimum requirements for the design, manufacture and testing of

a UL listed, air-cooled, outdoor weatherproof resistive load bank.

B. The load bank is required for periodic exercising and testing of the (standby) emergency power

source. The load bank shall be permanently mounted in a weatherproof enclosure, forced air
cooled with remotely mounted control panel.

C. This specification shall apply if the load bank is supplied to the purchaser, or as a part of other

equipment.

D. Should the vendor take exception to any part of this specification, it shall be stated in the bid, and

referenced to the specification line number.

1.2 SUBMITTALS

A. The manufacturer shall submit for review technical data including features, performance,

electrical characteristics, physical characteristics, ratings, accessories, and finishes.

B. Shop drawings shall include dimensional plans, front and side elevations and mounting details

sufficient to properly install the load bank. Load bus configuration and load connections
termination area shall be clearly identified.

C. Electrical schematic drawings shall be provided to detail the operation of the load bank and the

provided safety circuits. Over-current protection and control devices shall be identified and their
ratings marked. A system interconnection drawing shall be included for control wiring related to
the load bank.

1.3 STANDARDS

A. The equipment covered by this specification shall be designed with the latest applicable NEMA,

NEC, and ANSI standards.

B. The load bank shall be listed to UL Standard 508A.

PART 2.0 PRODUCTS

2.1 RATINGS

A. The total capacity of the load bank shall be rated (________) KW at (______) Volts, 3-Phase, 3-

Wire, 60 Hertz, (_______) Amps per Phase at unity Power Factor and (___) KW minimum load
step resolution.

B. The load bank shall be designed for continuous duty cycle operation with no limitations. The load

bank shall operate in an ambient temperature of -28°C to 49°C (-20°F to 120°F).

2.2 MATERIAL AND CONSTRUCTION

A. The load bank shall be outdoor weatherproof construction, suitable for installation on a concrete

pad or structural base. All exterior fasteners shall be stainless steel. The load bank shall include
forklift channels in the base for lifting.

9/2012-Rev C (K675A)

B. The load bank shall be constructed of heavy gauge aluminized steel per ASTM A463. Aluminized

steel provides superior corrosion protection and extended service life, with a better tolerance to
high heat exposure compared to the more common Galvanized steel.

C. The main input load bus, load step relays, fuses and blower/control relays shall be located within

the load bank enclosure. A thermostatically controlled heater shall be located within the control
section to provide protection to the control devices from the effects of moisture and condensation.

D. Airflow throughout the load bank shall be horizontal. Intake openings shall be designed to prevent

objects greater than 0.50″ diameter from entering the unit.

E. The load bank exhaust hood shall be angled downward. The exhaust hood shall be constructed

of non-corrosive aluminized steel or aluminum.

F. The load bank enclosure shall have a baked polyester powder coated finish with a film

thickness of 2.8 +/- 0.4 Mils per coat.

G. Load elements shall be contained in an integral resistor case. Resistors can be individually

removed for inspection or service.

2.3 RESISTIVE LOAD ELEMENTS

A. Load elements shall be Avtron Helidyne™, helically wound chromium alloy rated to operate at

approximately ½ of maximum continuous rating of wire. Elements must be fully supported across
the entire length within the air stream by segmented ceramic insulators on stainless steel rods.
Element supports shall be designed to prevent a short circuit to adjacent elements or to ground.

B. The change in resistance due to temperature shall be minimized by maintaining conservative watt

densities.

C. The overall tolerance of the load bank shall be –0% to +5% KW at rated voltage. A –5%, +5%

rating allows the load bank to deliver less than rated KW and shall not be used. The load bank
must deliver full rated KW at rated voltage.

2.4 COOLING

A. The load bank shall be cooled by integral TEFC or TEAO motor(s) which is direct coupled to the

cooling fan blade. The fan motor must be electrically protected against overload using a motor
overload device and short circuit protected using three (3) current limiting fuses with an
interrupting rating of 200K A.I.C.

B. The fan blade is to be an airfoil design constructed from aluminum or non-corroding material.

C. (OPTIONAL) An integral control power transformer shall be provided to supply 120V, 1 phase, 60

Hz to the load banks control and motor starter circuitry. Transformer primary and secondary
control circuits shall be fuse protected.

2.5 PROTECTIVE DEVICES

A. A differential pressure switch shall be provided to detect air loss. The switch shall be electrically

interlocked with the load application controls to prevent load from being applied if cooling air is
not present.

B. An over-temperature switch shall be provided to sense the load bank exhaust in the heater case

assembly. The switch shall be electrically interlocked with the load application controls to remove
load from being applied in the event of an over temperature condition.

9/2012-Rev C (K675A)