ID act - What is the meaning for protected workmen in industrial dispute act 1947?

What is the meaning for protected workmen in industrial dispute act 1947.
What should be the percentage of "protected workmen" of the total number of workmen employed in any establishment? ans is 1%. how to arrive 1% sir.

Section 33(3) of the Industrial Disputes Act provides certain privileges for a Protected Workman in an establishment.
Rule 61(1) of Industrial Disputes (Central) Rules, 1957, provides that every registered trade union connected with an industrial establishment shall communicate to the employer before the 30th April names and addresses of officials employed in the company and need to be recognised as Protected officials
1% of total strength of workmen
Minimum 5
Max 100
If there are more than one registered trade union,proportionate distribution needs ot be done.

Why those workmen are called protected workmen? And privileges a protected workman can enjoy? The Act is silent on this. Pl. clarify with examples.