(i) Mechanical Control for Constant – time equipment: A cam- operated
switch connected in the primary circuit of the welding transformer and driven
from the welding machine provides a simple device.
(ii) Valve-operated Control for Constant-time: Devices: To overcome the
difficulties encountered in the case of mechanically operated gears at high
speeds, various valve-operated devices have been developed, for example, the
mercury-vapour valve.
(iii) Current and energy- actuated control: With this control, current is allowed
to flow until a predetermined amount of energy has been supplied to the weld.
gregorymasila answered the question on February 20, 2018 at 16:05
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