Chapter 10 - Voltage Protection Functions
SENSITIVE OVERVOLTAGE SUPERVISION
Software versions 52 and 61 introduce Sensitive Overvoltage Protection (SOV). The SOV function provides an
extended range for the pickup setting (from 2V to 185V). The unique characteristic in SOV function extends the
relay's capability to mimic the buswire supervision function in a high impedance busbar protection scheme. P14x
relay can detect open circuit scenarios in buswire by using the sensitive overvoltage function. This enables the
P14x relay to provide cost & space efficient one box solution for both high impedance busbar protection and
SENSITIVE OVERVOLTAGE IMPLEMENTATION
The device provides two stages of Sensitive Overvoltage Supervision; SOV>1 and SOV>2. Two measurement modes
are available; phase-to-phase or phase-to-neutral. You choose the measurement mode with the SOV Meas't Mode
setting. Two operation modes are also available; any phase, or three-phase. You choose the operating mode with
the SOV Operate Mode setting. This setting determines whether any one of the phases or all three of the phases
have to satisfy the overvoltage criteria before a decision is made.
Both of these settings are global for both stages and cannot be applied individually to each stage.
Each stage can be enabled or disabled individually with the SOV>1 Status and SOV>2 Status settings. The pickup
threshold voltage for each stage can be set using, SOV>1 Volt Set and SOV>2 Volt Set settings respectively. A DT
time delay for each stage can also be set with the SOV>1 Time Delay and SOV>2 Time Delay settings.
SENSITIVE OVERVOLTAGE FILTER MODE
The SOV function also has SOV Filter Mode. When the SOV Filter Mode is enabled, the SOV protection provides
adaptive pickup responding to the frequency of the voltage input. In the SOV Filter Mode, the SOV function is
tuned to operate sensitively on nominal frequency, but adapt the pickup level to higher when the frequency is
outside nominal range.
The SOV function in SOV Filter Mode has a pickup setting range from 10V to 185V, this will respond to the relay's frequency
tracking range (40Hz to 70Hz). SOV protection in SOV Filter Mode will be blocked if the frequency of the voltage input is
outside the frequency tracking range.
It is possible to enable a band pass frequency characteristic for this function using the SOV Filter Mode setting. If
you set this to Disabled, the normal mode is chosen, which is no different from previous models. If you select
Enabled, however, this allows you to set the rate of operation voltage for various proportions of the system
frequency. You can set this individually from 0.8 times system frequency through to 1.2 times system frequency,
with the setting cells under the SOV OPERA CURVE sub heading.