hasattr error in system.py checkTensions func

## Description
system.py: Line 3332: hasattr(line.type,'MBL') returns false
However MBL exists.

this issue is in other places. this is just one example

### Current behavior
system.py: Line 3332: hasattr(line.type,'MBL') returns false
However MBL exists.

### Expected behavior
system.py: Line 3332: hasattr(line.type,'MBL') returns True

fix:
system.py: Line 3332: 'MBL' in line.type 