strtotime function for hours more than 24 in php

I am working with OT system .i want compare two time variable more than 24. first value coming from the following function.

function GetApprovedOt($connect,$emp_id,$passmonth)
  {
      $query01 ="SELECT SEC_TO_TIME( SUM( TIME_TO_SEC( `ot_hour` ) ) ) AS timeSum 
                 FROM otresquest
                 WHERE em_id = $emp_id AND  from_month LIKE '$passmonth%' AND overtime_status=6";
      $statement = $connect->prepare($query01);

      if($statement->execute())
      {  

        $result = $statement->fetchAll();
        foreach($result as $row){

              $sum =$row["timeSum"];
              return $sum;
             }   
       }
  } 

i write function to get the time value using following function.

function formatHours($time){
    $date = explode(':', $time);
    return ($date[0]*60*60)+($date[1]*60)+$date[2];
}

    if(formatHours($time_duration_1) > formatHours($time_duration_2)){

my problem is formatHours function working for single value pass in to the function like formatHours($row["ot_hour"]) but i try to pass value of GetApprovedOt($connect,$row["emp_id"],$_GET["month"]) get error like

Notice: Undefined offset: 1 in C:\xampp\htdocs\attendance\admin\report05.php on line 243

Notice: Undefined offset: 2 in C:\xampp\htdocs\attendance\admin\report05.php on line 243

Line 243 is return ($date[0]*60*60)+($date[1]*60)+$date[2]; how do void this error ?how appreciate yours valuable contribution