The switching apparatus includes {HEAD ~ one or more sensing devices} for detecting the condition of {TAIL ~ the system}, directly or indirectly 
The switching apparatus includes { HEAD ~ one or more sensing devices } for detecting the condition of { TAIL ~ the system } , directly or indirectly
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH