ABB RED615 Product Manual - page 17
7. Measurements
The relay continuously measures the phase currents, the
symmetrical components of the currents and the residual
current. If the relay includes voltage measurements, it also
measures the residual voltage. The relay also calculates the
demand value of the current over a user-selectable, pre-set
time frame, the thermal overload of the protected object, and
the phase unbalance based on the ratio between the negative-
sequence and positive-sequence current.
Furthermore, the relay monitors the phase differential, bias and
remote-end phase currents.
The values measured can be accessed locally via the user
interface on the relay's front panel or remotely via the
communication interface of the relay. The values can also be
accessed locally or remotely using the Web browser-based
user interface.
The relay is provided with a load profile recorder. The load
profile feature stores the historical load data captured at a
periodical time interval (demand interval). The records are in
COMTRADE format.
8. Power quality
In the EN standards, power quality is defined through the
characteristics of the supply voltage. Transients, short-duration
and long-duration voltage variations and unbalance and
waveform distortions are the key characteristics describing
power quality. The distortion monitoring functions are used for
monitoring the current total demand distortion and the voltage
total harmonic distortion.
Power quality monitoring is an essential service that utilities can
provide for their industrial and key customers. Not only can a
monitoring system provide information about system
disturbances and their possible causes, it can also detect
problem conditions throughout the system before they cause
customer complaints, equipment malfunctions and even
equipment damage or failure. Power quality problems are not
limited to the utility side of the system. In fact, the majority of
power quality problems are localized within customer facilities.
Thus, power quality monitoring is not only an effective customer
service strategy but also a way to protect a utility's reputation
for quality power and service.
The protection relay has the following power quality monitoring
functions.
• Voltage variation
• Voltage unbalance
• Current harmonics
• Voltage harmonics
The voltage unbalance and voltage variation functions are used
for measuring short-duration voltage variations and monitoring
voltage unbalance conditions in power transmission and
distribution networks.
The voltage and current harmonics functions provide a method
for monitoring the power quality by means of the current
waveform distortion and voltage waveform distortion. The
functions provides a short-term 3-second average and a long-
term demand for total demand distortion TDD and total
harmonic distortion THD.
9. Fault location
RED615 features an optional impedance-measuring fault
location function suitable for locating short-circuits in radial
distribution systems. Earth faults can be located in effectively
and low-resistance earthed networks. Under circumstances
where the fault current magnitude is at least of the same order
of magnitude or higher than the load current, earth faults can
also be located in isolated neutral distribution networks. The
fault location function identifies the type of the fault and then
calculates the distance to the fault point. An estimate of the
fault resistance value is also calculated. The estimate provides
information about the possible fault cause and the accuracy of
the estimated distance to the fault point.
10. Disturbance recorder
The relay is provided with a disturbance recorder with up to 12
analog and 64 binary signal channels. The analog channels can
be set to record either the waveform or the trend of the currents
and voltages measured.
The analog channels can be set to trigger the recording function
when the measured value falls below, or exceeds, the set
values. The binary signal channels can be set to start a
recording either on the rising or the falling edge of the binary
signal or on both.
By default, the binary channels are set to record external or
internal relay signals, for example, the start or trip signals of the
relay stages, or external blocking or control signals. Binary relay
signals, such as protection start and trip signals, or an external
relay control signal via a binary input, can be set to trigger the
recording. Recorded information is stored in a non-volatile
memory and can be uploaded for subsequent fault analysis.
11. Event log
To collect sequence-of-events information, the relay has a non-
volatile memory with a capacity of storing 1024 events with
associated time stamps. The non-volatile memory retains its
data also in case the relay temporarily loses its auxiliary supply.
The event log facilitates detailed pre- and post-fault analyses of
feeder faults and disturbances. The increased capacity to
process and store data and events in the relay offers
prerequisites to support the growing information demand of
future network configurations.
The sequence-of-events information can be accessed either
locally via the user interface on the relay's front panel, or
remotely via the communication interface of the relay. The
Line Differential Protection and Control
1MRS756500 K
RED615
Product version: 5.0 FP1
ABB
17