Motor operator for over-head air break electrical power distribution switches

Abstract

A motor operator for an overhead power switch is disclosed including a microcontroller, a unique and powerful array of well-integrated sensors, a motor and drive developing substantial torque and speed and coupled to a switch actuator and responsive to the microcontroller, and a sophisticated program algorithm stored in memory at the actuator site for dynamically controlling, i.e., governing the various control modes as called for by changing conditions. The sensors include an encoder associated with the motor and drive that develops position information signals fed to the dynamic microcontroller to compute real time information including position, speed, and stopping distance used in conjunction with remote operate commands to open, close and monitor status of the switch in the various ways disclosed. Under the supervision of the microcontroller, a motor drive power switching circuit selectively applies a source of power, such as from an on site battery, to an electric motor to drive the switch toward open or closed position at different speeds, output force levels such as at different torques, and in continuous or incremental movements depending on conditions determined by the microcontroller in response to sensor inputs.

Description

[0001] This is a continuation-in-part of provisional U.S. application Ser. No. 60 / 080,718 filed Apr. 03, 1998.[0002] 1. Field of the Invention[0003] The present invention relates to remotely controlled actuators for opening, closing and monitoring status of electrical power distribution switches of the type commonly used on overhead pole installations which close the contacts to carry high current--voltage and open to break the circuit with an ambient air gap separating the contacts.[0004] 2. Background Art[0005] The most predominant method for routing electrical power to utility customers is through the use of single or three-phase electrical circuits carried on overhead power distribution lines. To allow these circuits to be disconnected, rerouted or otherwise reconfigured, air-break, single or gang-operated three-phase switches are commonly employed. These switches are typically mounted at the top of a wood, steel or concrete pole, and the operating actuator is typically carried ...

AI Technical Summary

Benefits of technology

The system ensures reliable and precise operation of electrical power distribution switches, preventing damage and arcing, while providing remote monitoring and maintenance indications, and automatically recovering from failure conditions, thus enhancing operational safety and efficiency.

Problems solved by technology

However, many problems arise as environmental factors cause changes to the operating conditions of the switch assemblies, operators and available energy in batteries.

These problems can result in improper switch operation with potentially serious implications.

The most obvious problems result from one or more of the switch contacts becoming stuck to its mating surface due to a buildup of ice or due to welding (caused by high-current surges related to lightning discharge).

Unless the breaker automatically resets, the switch will require immediate, human intervention, and even with automatic resetting, further successful operation is unlikely.

A further undesirable circumstance is that the mechanism is tensioned to open.

Another problem relates to variations in the force necessary to overcome the problem of stuck or sticky switch contacts and debris or ice buildup.

The operator must be designed to apply the necessary force without applying so much force that the switching mechanism is readily damaged.

Since the force applied to the switch depends on many factors, this is a difficult problem to solve with a simple, electromechanical design.

Another problem results from uncontrollable variations in speed of operation.

They are also caused by variations in the condition of the switching mechanism including slack, corrosion, etc.

Changes in stopping distance based upon variation in speed at time of limit switch contact cannot be adequately taken into account in such an electromechanical arrangement.

Another problem with existing designs is the difficulty in creating indications for the remote operator when something otherwise obvious is wrong.

Although proximity sensors can be deployed to detect these conditions, these sensors must be placed in hostile, outdoor environments that are costly to properly instrument and unreliable in function.

Another problem relates to the complexity of adjusting the digital limit switches, and to their inherent unreliability.

The mechanical adjustment of these switches is difficult to perform reliably, with only very subjective criteria for correct setting.

Another problem relates to the method of coupling the operator to the switch.

These couplings are problematic and can slip during high-torque operation, causing the switch to go out of adjustment.

Another problem relates to the dangerous situation posed by a lineman operating the device from the front panel.

Existing designs have no way to allow the operator to get out of the way before the switch operates.

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