100% Stator Ground100% Stator Ground(59N/27TH)(59N/27TH)

Stator Ground ProtectionStator Ground ProtectionProvides protection for stator ground fault on generators which are high impedance groundedUsed on unit connected generatorsGround current limited to about 10A primary

Provides 100% stator ground protection (entire winding)

High Impedance Grounding

3rd Harmonic Comparator for 100% 3rd Harmonic Comparator for 100% Stator Ground Fault ProtectionStator Ground Fault Protection

3rd harmonic levels change with position of ground fault and loading

Using a comparator technique of 3rd harmonic voltages at line and neutral ends allows an overvoltage element to be applied

Third-Harmonic Undervoltage Ground-Fault Protection Scheme

100% Stator Ground Fault (59N/27TN)

Settings summary per IEEE C37.102

59G element: Pickup = 5 V; t = 5 s Note: Time setting must be selected to provide coordination with other system protective devices.

27TH element: Pickup = 50% of minimum normal generator 3rd harmonic. t = 5 s

Stator GroundStator Ground