<?php
$saatler = array(
    '02:00:00',
    '00:38:00',
    '00:00:00',
    '00:00:00',
    '00:00:00',
    '00:00:00',
    '00:00:00'
);

$hour = 0;
$minute = 0;
$second = 0;

foreach($saatler as $saat) {
    $parcala = explode(':', $saat);
    $hour = $hour+intval($parcala[0]);
    $minute = $minute+intval($parcala[1]);
    $second = $second+intval($parcala[2]);
}

if($second > 59) {
    $minute = $minute+intval($second / 60);
    $second = $second % 60;
}

if($minute > 59) {
    $hour = $hour+intval($minute / 60);
    $minute = $minute % 60;
}

if(strlen($hour) == 1) { $hour = '0'.$hour; }
if(strlen($minute) == 1) { $minute = '0'.$minute; }
if(strlen($second) == 1) { $second = '0'.$second; }

echo $hour.':'.$minute.':'.$second;
?>