Advantages of Spring Control Method:
1) The spring-controlled meters may be used in any position.
2) In some instruments, springs can be used as current leads.
3) As springs are light in weight, practically there is no increase in weight of the
moving system hence high torque to weight ratio.
4) The spring-controlled meters have uniform scale.
Disadvantages of Spring Control Method:
1) Temperature change affects spring length causing change in magnitude of
2) Accidental stress in the springs may damage them.
3) Spring will not respond if stressed beyond their elastic limit.
4) Controlling torque cannot be adjusted easily.
Advantages of Gravity Control Method:
1) It is very simple method.
2) It is economical method.
3) It is unaffected by temperature changes.
4) It is not subjected to fatigue.
5) Controlling torque can be adjusted easily by control weight.
Disadvantages of Gravity Control Method:
1) Instrument should to kept in vertical position only.
2) Scale is non-uniform.
3) Control weights add to the weight of instrument.