Need to add 30 sec save

Hi i need to add 30 sec nopvp
and NOPVP is 30
but i dont now how to add this
i have try this but now i can fight 1x after 30 sec
if ($a->GAME_STATE == 1 and $this->time % $this->pg->configs['NOPVP'] = 0)
$ev->setCancelled();

Spoiler

Code:

public function onDamage(EntityDamageEvent $ev)
     {
         $this->time++;
         if ($ev->getCause() == 0b100 or $ev->getCause() == 0b1100 or $ev->getCause() == 0b11) {
             $ev->setCancelled();
             return;
         }
         foreach ($this->pg->arenas as $a) {
             if ($ev->getEntity() instanceof Player) {
                 if ($a->inArena($ev->getEntity()->getName())) {
                     if ($ev->getCause() == 0b1111 and $this->pg->configs['starvation_can_damage_inArena_players'] == false)
                          $ev->setCancelled();
                      if ($a->GAME_STATE == 0)
                          $ev->setCancelled();
                     if ($a->GAME_STATE == 1 and $this->time % $this->pg->configs['NOPVP'] = 0)
                         $ev->setCancelled();
                      break;
                  }
              }

GAME_STATE == 1 is game started

https://github.com/Driesboy/SurvivalGames/blob/master/php7/src/svile/sw/SGlistener.php#L270

is the github file

Maybe look into the code of TimeCommander - LDX, because that has a timer function