Annex 10

Preventive Maintenance Schedule for Protection Systems

S. No.	Tasks assigned	Shut Down (SD) Or Without Shut Down (WSD)	Periodicity
a.	Testing of DR/EL	WSD	Monthly
b.	Calibration of panel meters (Indicating/Recording instruments along with the transducers)	WSD	Yearly
c.	Calibration of Non-Tariff Energy meters	WSD	Yearly
d.	Calibration of Tariff Energy Meters
e.	Secondary Injection Test of individual protection schemes	SD	Yearly
f.	Checking of Voltage (in service) for relays	WSD	Yearly
g.	Checking of DC drain of static relays	WSD	Yearly
h.	Checking of DC drain of static relays	WSD	Yearly
I.	LINE PROTECTION
A.	DISTANCE PROTECTION
	MICROMHO
	Reach check for all 4 zones*	WSD	Yearly
	Time measurement	WSD	Yearly
	Power swing blocking check	WSD	Yearly
	SOTF	WSD	Yearly
	Level detectors of pps	WSD	Yearly
	Fuse failure check	WSD	Yearly
	Polarization check	WSD	Yearly
	Nps detector check	WSD	Yearly
	YTG
	Reach check for all 4 zones**	WSD	Yearly
	Timing check for the same	WSD	Yearly
	PSB check	WSD	Yearly
	DC Supply monitoring	WSD	Yearly
	VT fuse failure check	WSD	Yearly
	RAZFE
	Reach check for all 4 zones**	WSD	Yearly
	Timing check for the same	WSD	Yearly
	PSB check	WSD	Yearly
	VT fuse failure check	WSD	Yearly
	LZ 96
	Reach check for all 4 zones**	WSD	Yearly
	Timing check for the same	WSD	Yearly
	PSB check	WSD	Yearly
	Opto coupler inputs check
	Self diagnostic signals check
	SOTF check
	VT fuse failure check	WSD	Yearly
	THF Reyrolle
	Reach check for all 4 zones**	WSD	Yearly
	Timing check for the same	WSD	Yearly
	PSB check	WSD	Yearly
	SOTF check
	VT fuse failure check	WSD	Yearly