2021 RSS Manual all models.doc. Page 6 // 02/12/21
MOTOR ELECTRICAL SYSTEM-The electric motor is a capacitor start induction motor with an
internally switched starting capacitor and with internal thermal protection. Service cord replacement
is allowed. Use 16 gauge or heavier flexible copper service cords not more than 12 feet (3.5 m) long.
Bayonet terminals are used. If installing replacement cord has lug nut connectors, use extreme
caution in applying torque to the terminal screw connector-nuts. Rotation of the terminal studs will
cause internal motor shorts and motor burnout. Jumper connections internal to the motor (e.g. red vs.
black) shall not be changed during inspections or service wire replacement because the direction of
rotation will change. The direction of fan wheel rotation (counter - clockwise looking down into
the unit) is mandatory for proper calibration.
MOTOR SECURITY-The motor bolts and lock nuts need not normally be inspected unless repair or
inspection requiring removal of the motor is performed. Upon re-assembly, torque the motor bolts and
lock nuts to 8 ft-lb. (1.1 kg-m) before placing the RSS into routine use.
MOTOR LUBRICATION- Oil ports are not provided. This RSS motor has ball bearings that should
operate quietly for at least 10 years. After 10 years if any squeaking sound is heard from the bearings,
the motor end bells may be removed, and the bearings lubricated by massaging new grease into the
bearing races.
CARRYING FRAME-The frame of the RSS is reinforced with lateral braces to prevent frame
bending in shipment. The motor and fan should stand erect + 3 degrees within the frame. If the motor
bolts have loosened, then realign and tighten bolts per "MOTOR SECURITY" above. If the motor
support or frame is bent, but the motor/fan wheel axis tilt is less than 4 degrees, no corrective action
is necessary. Larger deformations or bent frame members should be corrected by good metal (steel)
shop practices after removal motor/fan wheel as a unit by unfastening the four motor bolts. Take
precautions to NOT apply any deforming forces to fan wheel during removal, storage, and
replacement. Store motor/fan wheel on a short 1-1/2" thick board since fan wheel radius is 1-1/2"
greater than motor shaft height. Replace motor/fan wheel per “MOTOR SECURITY".
SPRING ISOLATOR FEET: Each retainer bolt head projects above and clears the frame plate by
1/8” to 3/16” when the RSS stands on its feet. Adjust by rotating the bolt if needed.
PERIODIC ACOUSTICAL CHECK AND CALIBRATION: The RSS should produce a constant
sound field indefinitely as long as proper electrical power is applied, and no damage has occurred to
the unit. However, significant fan wheel or motor damage and/or dust accumulation can alter the
sound power output. Dust can be removed as described in FAN WHEEL CONDITION.
Periodic acoustic checks of the RSS as described in ISO 6926/ANSI S12.5 section 5.6.3 at least
every 6 months or any time the unit appears to have incurred damage. Units that are regularly
transported to field locations may need to have the period check performed more frequently.
Recalibration according to ISO 6926 is advised when fan wheel or surge band damage have been
repaired, when fan wheel RPM deviates constantly more that 1 % from the RPM reported at the
calibration voltage or when more than ten (10) years have elapsed since the last calibration.
Calibration should be performed in a laboratory operating in accordance with ISO 6926/ANSI S12.5,
Free Field over a Reflecting Plane.
SERVICE DIFFICULTY, SHIPPING AND FACTORY REPAIRS: In case of difficulties, contact
VIacoustics for further help and instructions. Do NOT load this bare-framed instrument surrounded
by only bubbles or pellets, as the fan wheel can be damaged in this environment. It is recommended
that RSS units be shipped in the robust carrying case/shipping container provided by VIacoustics.
