Schweitzer Engineering Laboratories, Inc.
SEL- 2664S Data Sheet
3
Protection and Control Features
➤
Stator Insulation Protection.
The 64S element of
the SEL-2664S uses multisine signal injection at
generator neutral to monitor 100 percent of the sta-
tor insulation. The element works with the genera-
tor in- or out-of-service, including the generator
ramp up, with no blind period. Two levels of 64S
elements provide warning and trip along with delay
and torque control settings. The 64S elements
require neutral voltage below an allowable injection
voltage level and, together with the 59N elements
described later, provide 100 percent stator ground
protection 100 percent of the time.
➤
Rotor Field Ground Protection.
An SEL-2664S
Relay connected to an SEL-2664 Field Ground
Module detects field ground faults by measuring
field insulation-to-ground resistance with the
switched dc voltage injection method. Two-level
protection for warning and trip functions along with
delay and torque control settings is provided. The
module transmits the insulation resistance value to
the relay through a fiber-optic cable with ST
connectors.
➤
Neutral Overvoltage Protection.
The SEL-2664S
provides two neutral overvoltage elements. The
59N1 element uses the fundamental frequency
magnitude of neutral voltage (VN), and the
59NRMS element uses the rms magnitude of VN.
The relay provides one level from each of the 59N1
and 59NRMS elements for trip, along with delay
and torque control settings. The 59N elements are
independent of the 64S elements described previ-
ously. The combination of the two, with their over-
lapping coverage, provides 100 percent stator
winding protection 100 percent of the time.
➤
Neutral Ground Resistor Monitor.
The SEL-2664S
monitors the generator neutral grounding resistor
(NGR) value using NGR elements and operates
when a short or an open circuit is detected.
Figure 2
SEL-2664S
Multisine Injection Signal
Waveform
Metering and Monitoring
Metering Functions
The SEL-2664S provides metering for neutral voltage
and current. The relay meters injection source currents
and voltages, stator insulation resistance and capacitance,
and neutral ground resistance. The relay also meters field
insulation resistance when used with the SEL-2664 Field
Ground Module. Refer to
for detailed
descriptions.
Table 1
Metered Quantities
(Sheet 1 of 2)
Quantities
Description
Stator Insulation (k
)
Resistance of the stator insulation to ground in kilohms, primary
Stator Insulation (uF)
Capacitance of the stator insulation to ground in microfarads, primary
Neutral Ground Resistor (
)
Resistance of the neutral grounding resistor in ohms (secondary or primary based on NGR
location)
Field Insulation (k
)
Resistance of field insulation to ground in kilohms
Neutral Voltage (V sec)
Magnitude of fundamental, third-harmonic, and rms neutral voltage in secondary volts
Neutral Current (A sec)
a
b
RMS and third-harmonic magnitudes of neutral currents in secondary amperes
Neutral Current (A pri)
a
RMS and third-harmonic magnitudes of neutral currents in primary amperes
Injected Current (A sec)
a
RMS magnitude of injected current in secondary amperes
Injected Voltages (V at NGR Tap)
Voltage magnitude of specific frequency at the NGR Tap
