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Rotary limit switches

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TER has acquired decades of experience in designing and manufacturing rotary limit switches, providing now four series of rotary limit switches, used to control the movement of industrial machinery when in need of measuring the movement on the basis of the rotation angle and/or of the number of shaft revolutions.
rotary limit switches are used in particular in industrial and construction lifting plants to control gantry cranes, track cranes, jib cranes, wall-mounted jib cranes, tower cranes and winches for construction sites; in the automation industry to command and control systems to manage machines and processes, thus reducing the need for human intervention; in stage technology to control the equipment used to move stage sets, curtains etc.; on wind turbines for managing and controlling the pitch angle of the blades (pitch control) and the position of the nacelle (yaw control).

These machines operate in difficult thermal conditions (low or high operating temperatures) with great thermal shifts between night and day, and they are subject to a variety of weather conditions (water, dust, UV rays and salt). They therefore need components with a high degree of protection against weather effects, resistance to extreme temperatures, high mechanical and electrical durability and resistance, accuracy in control. All components must be precise, reliable and safe to ensure good handling control, guarantee maximum operating safety, prevent personal injury and damage to objects, and prevent collisions and impact when a number of machines of the same type or similar are present in the same area.

TER range of rotary limit switches includes four series of limit switches, with revolution ratios ranging from 1:1 to 1:8100 and up to 15 microswitches with potentiometers and encoders.
The rotary limit switch is made up by a gearmotor which transfers the movement to the cams and to the other movement detection devices placed inside it through a primary input reduction step (worm gear and helical toothed gear) and one or more secondary output steps (pairs of straight toothed gears).
The movement is transferred from the motor to the shaft of the rotary limit switch which, thanks to a combination of cam switches, potentiometers and encoders ensures maximum operating safety and efficiency.
On wind turbines rotary limit switches are used to control the position of the nacelle or the pitch angle of the blades. The motor that controls the rotation of a wind turbine on the yaw axis (or of the blade around its longitudinal axis) transfers the movement to the limit switch. A rotary encoder reads the rotation of the shaft, and its pulses are sent to a PLC which controls the position of the nacelle or of the blade. The movement of the shaft is also transferred, through a gearmotor, to a series of cam switches: the appropriate setting of the actuating point of the cams can signal up to four critical positions of the movement of the nacelle or of the blade.
Each series of rotary limit switch has specific features which drastically reduce time and costs for installation and maintenance down time.
The rotary limit switch Base has small overall dimensions suitable for assembly in narrow spaces. Revolution ratios range from 1:15 to 1:1500. Base can be equipped with cam sets with a maximum of 6 switches and it has one output only. The limit switch is available with direct control switches to operate directly on the motor.
The rotary limit switch Fox has revolution ratios ranging from 1:3 to 1:2870 and it can be fitted with different combinations of actuators and motion detectors: up to 5 cams and microswitches, one potentiometer or encoder, one absolute encoder Yankee 1.
The rotary limit switch Oscar has revolution ratios ranging from 1:1 to 1:1550 and it can be equipped with different combinations of actuators and motion detectors: up to 12 cams and microswitches, 2 potentiometers, encoders or absolute encoders Yankee 1. Oscar features two outputs that can be set with different revolution ratios to allow for a diversified control of the machinery to meet special requirements. Oscar can be fitted with up to 8 cable clamps or dedicated connectors.
The rotary limit switch Top has revolution ratios ranging from 1:1 to 1:8100 and it can be fitted with different combinations of actuators and motion detectors: up to 15 cams and microswitches, 3 potentiometers, encoders or absolute encoders Yankee 1. Top has three outputs that can be set with the same or with different revolution ratios to allow for a diversified control of the machinery to meet special requirements. Oscar can be fitted with to 2 cable clamps for cable entry.
The enclosure of the rotary limit switch Top is made of electrostatic varnished die-cast aluminum, ensuring optimal wear and saline fog resistance.
rotary limit switches Fox, Oscar and Top can be equipped with the electronic position sensor Yankee 1 to control multi-revolution rotors. Yankee 1 Yankee 1 interfaces with rotation elements and returns a signal according to the angular position to meet any need in terms of registration and identification of modern production machines, wherever controls are needed, regardless of the nature of the mechanic system and of its complexity, and to reduce and unify the system of angular positioning sensors. The measuring accuracy is guaranteed by 4096 points per revolution.
The option of fitting together sets of cams and microswitches, potentiometers, encoders and Yankee 1 in the rotary limit switches, provides devices featuring redundancy and diversity.
rotary limit switches are available with couplings, pinion gears or flanges for direct coupling to the motor, plates with universal adapter to replace existing systems, cable clamps or dedicated connectors.
Each cam can be set with great accuracy thanks to the cam adjusting screws.
All NC contacts are the positive opening type for safety functions .
All rotary limit switches are tested to operate at an ambient temperature ranging from -40C to +80C.
The enclosures of the limit switches are made of wear resistant techno-polymers or of electrostatic varnished die-cast aluminum (Top limit switches) making the unit saline fog resistant.
The shafts are made of stainless steel AISI 430F or high resistance stainless steel AISI 303. Gears and driving bushes are made of self-lubricating techno-polymers suitably chosen to reduce the wear to a minimum and to maintain the accuracy of the couplings over time.
All the materials and components used are weather resistant and guarantee protection of the units against the penetration of water and dust.
Each rotary limit switch features different degrees of protection: IP65 (water jets), IP66 (strong high-velocity water, 100 litres/minute), IP67 (temporary immersion), IP69K (high-pressure/steam-jet cleaning water) and they are all totally protected against the penetration of dust.

All rotary limit switches are CE marked and they are manufactured in compliance with the Directives and Standards in force. Some TER rotary limit switches are UL certified for the American market, CSA certified for the Canadian market and they are all EAC certified for the Eurasian markets (Russia, Belarus, Kazakhstan) as proof of the importance given to the quality levels required in different countries.
All rotary limit switches conform to the regulations for the prevention of accidents BGV C1 (only for Germany).
Fox, Oscar and Top can be certified SIL 1, referring to the integrity level required of a component to be suitable to perform a safety function for a given time and under specific conditions of use.
Furthermore, rotary limit switches Fox and Oscar have passed the HALT Tests (Highly Accelerated Life Test), a simulation of conditions largely exceeding the standard operating conditions.
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TER Tecno Elettrica Ravasi srl
Sede Operativa / Headquarter
Via Garibaldi 29/31
23885 Calco (LC) - Italy
Tel. +39 039 9911011
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