SERIES 70 ELECTRIC ACTUATOR
Installation, Operation, and Maintenance Manual
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© 2022 BRAY INTERNATIONAL, INC. ALL RIGHTS RESERVED. BRAY.COM
The Information contained herein shall not be copied, transferred, conveyed, or displayed in any manner
that would violate its proprietary nature without the express written permission of Bray International, Inc.
2.0 INTRODUCTION
The Bray Series 70 is a quarter turn electric actuator with manual override for use on
any quarter turn valve requiring up to 18,000 lb-in [2,034 N m] of torque. Operating
speeds vary between 30 to 110 seconds.
2.1
Principle of Operation
The Series 70 actuator is divided into two internal sections, the power center below
the switch plate, and the control center above the switch plate. Below the switch
plate, the gear motor, with its spur gear train, drives a non-backdriveable worm gear
output. The override mechanism for manual operation is also housed here. Above
the switch plate is where user required readily accessible components are placed.
The indicator shaft assembly, limit switches, terminal strips, torque switches, heater,
and electronic controllers are all placed here for easy access.
External to the unit are adjustable mechanical travel stops, a large and easy to read
indicator, the unique manual override handwheel, and dual conduit entry ports. The
external coating is a high-quality polyester powder coat which has exceptional UV
protection and chemical resistance.
2.2
Electrical Operation
The gear motors used in the Bray Series 70 are of either permanent split capacitor
(PSC) design (single phase AC power) or permanent magnet (PM) design (DC
power). Travel limit switches are mechanical form (SPDT) with contacts rated at 10
Amp (0.8 PF), 1/2 HP 125/250 VAC.
In cases where the torque capacity of the unit is exceeded to the point where the
motor stalls, a thermal protector switch, built into the PSC motor windings, will
automatically disconnect the motor power and prevent overheating. Once the motor
cools sufficiently, the thermal protector switch will reset automatically.
Optional torque switches are available in all units to prevent the possibility of stalling
the motor, thus reducing the possibility of an inoperable thermal cool down period.
Torque switches, installed by Bray, are factory adjusted to the output torque rating
of the unit using electronic torque testing equipment.
2.3
Mechanical Operation
Mechanically, the ratio of the gear motor determines the speed of the unit. The gear
motor utilizes high efficiency spur gears with various ratios for the different speeds.
Initial gear reduction through the spur gears is then transferred to the worm shaft.
The final gear reduction and output is through a non-backdriveable worm gear set.
Positioning is determined by an indicator/cam shaft, which is linked to the output
shaft. In the declutchable condition, the manual override drives the worm shaft
when engaged.
