What is a spring control?

This is the most common method of providing controlling torque in electrical instruments. A spiral *hairspring made of some non-magnetic material like phosphor bronze is attached to the moving system of the instrument as shown in Fig. ( a).

What is the gravity control?

Gravity controlled instruments are used for producing controlling torque and will be independent of temperature. In such instruments, the moving system when deflecting through an angle θ, from its position produces controlling torque (Tc). A small weight, W is attached to the moving arm.

What are the disadvantages of gravity control?

Disadvantages of Gravity Control

• Since the controlling torque is proportional to the sine of the angle of deflection, the scale is not uniformly divided but cramped at its lower end.
• It is not suitable for use in portable instruments (in which spring control is always preferred).

What is gravity control backward torque?

Gravity Control: In this method, a small adjustable weight W is attached to the moving system which provides the necessary controlling torque. Under the action of deflecting torque, the pointer moves from zero position (from left to right), and the control weight moves in the opposite direction.

What are the requirements essential to employ spring control to an instrument?

To employ spring control to an instrument, following requirements are essential.

• The spring should be non-magnetic.
• The spring should be free from mechanical stress.
• The spring should have a small resistance, sufficient cross-sectional area.
• it should have Low resistance temperature co-efficient.

Which material is used to make control spring in measuring instruments?

For most applications phosphor bronze has been found to be the most suitable material except in instruments low in resistance (like multi-voltmeters).

What is the advantage of gravity control instruments?

Detailed Solution. Advantages of Gravity Control: It is slightly cheaper in manufacturing costs as compared to spring control. It is unaffected by temperature variations.

Which type instrument is using gravity control?

A gravimeter is an instrument which measures extremely small changes in weight. The weight of a mass varies with changes in the gravitational field. To detect a change in weight (force of gravity) of 0.1 mgal, a gravimeter must have a sensitivity of lO-‘g.

What will be the advantages of gravity controlling?

What are the different control torques?

In order to ensure proper operation of indicating instruments, the following three torques are required: Deflecting torque. Controlling torque. Damping torque.

Which torque is absent in energy meter?

In energy meter, there is no controlling torque, as the driving torque alone is enough to cause continuous revolution of the disc. 12.

What is the position to use the instrument provided with spring control?

SPRING CONTROL One spring is placed above while other spring is placed below the spindle of the instrument.