user4418: The FIDE Rating Regulations say

For a game to be rated each player must have the following minimum
  periods in which to complete all the moves, assuming the game lasts 60
  moves. Where at least one of the players in the game has a rating 2200
  or higher, each player must have a minimum of 120 minutes.

When increments are used this has resulted in the almost standard time control of all moves in 90 minutes with a 30 second increment from move 1. That way each player has 90 minutes plus 30x60 seconds for 60 moves = 2 hours.
If delay is used instead of increments what is the equivalent time control?
It seems to me that game in 90 minutes plus 30 second delay would not satisfy the requirement for a minimum of 120 minutes for 60 moves. Particularly in the opening players will play moves in under 30 seconds as so have less than 120 minutes for 60 moves. 
To guarantee 120 minutes playing time for 60 moves and writing all the moves down would require game in 120 minutes plus 30 second delay.
I have seen 40 moves in 100 minutes, then 60 minutes to finish the game plus 30 second delay from move 1 but this is more generous as each player will have a minimum of 160 minutes, not 120 minutes for 60 moves.

user13524: That players will typically not use the full extent of the delay is not relevant. The minimum time requirement refers to the least upper bound of the possible amounts of time the players could theoretically take. Thus, G/90 d30 satisfies the requirement, although it is a very uncommon control.

4418: <p>The <a href="https://www.fide.com/component/handbook/?id=197&amp;view=article" rel="nofollow noreferrer">FIDE Rating Regulations</a> say</p>

<blockquote>
  <p>For a game to be rated each player must have the following minimum
  periods in which to complete all the moves, assuming the game lasts 60
  moves. Where at least one of the players in the game has a rating 2200
  or higher, each player must have a minimum of 120 minutes.</p>
</blockquote>

<p>When increments are used this has resulted in the almost standard time control of all moves in 90 minutes with a 30 second increment from move 1. That way each player has 90 minutes plus 30x60 seconds for 60 moves = 2 hours.</p>

<p>If delay is used instead of increments what is the equivalent time control?</p>

<p>It seems to me that game in 90 minutes plus 30 second delay would not satisfy the requirement for a minimum of 120 minutes for 60 moves. Particularly in the opening players will play moves in under 30 seconds as so have less than 120 minutes for 60 moves. </p>

<p>To guarantee 120 minutes playing time for 60 moves and writing all the moves down would require game in 120 minutes plus 30 second delay.</p>

<p>I have seen 40 moves in 100 minutes, then 60 minutes to finish the game plus 30 second delay from move 1 but this is more generous as each player will have a minimum of 160 minutes, not 120 minutes for 60 moves.</p>
 13524: <p>That players will typically not use the full extent of the delay is not relevant. The minimum time requirement refers to the least upper bound of the possible amounts of time the players could theoretically take. Thus, G/90 d30 satisfies the requirement, although it is a very uncommon control.</p>
