S&C Instruction Sheet 659-520
27
Utility Commanded Islanding with Closed Transition Return:
In this mode, the
utility has control of the opening and closing of the island circuit breaker. When an
island is detected, the utility commands the island circuit breaker open. When the
PureWave SMS-250 sees a UDM overvoltage or a UDM undervoltage, or an overfrequency
or underfrequency, and the island circuit breaker feedback voltage (24 V) is removed,
the PureWave SMS-250 will move to the
Island
mode. After the utility returns and is at
a normal voltage and frequency for 300 seconds (configurable on the
Configuration—
Field Parameters
HMI screen), the PureWave SMS-250 system will synchronize with the
utility. When synchronized, the PureWave SMS-250 system will turn on the
Synchro-
nized to Utility
alarm and set the SCADA status point. When the utility sees that the
ac voltage is good and the PureWave SMS-250 system is synchronized, it can close the
island circuit breaker. When the island circuit breaker feedback voltage (24 V) returns,
indicating that the island circuit breaker is closed, the PureWave SMS-250 system will
stop islanding.
NOTICE
Islanding Breaker Feedback must be configured so there is voltage (24 Vdc when the
island circuit breaker is closed and the voltage (24 Vdc) is removed when it is open .
For this mode, the user must use the
Configuration—Field Parameters
HMI screen
and configure the following:
Islanding Enable
—Feature Enabled
Utility Voltage Feedback
—Feature Enabled
Island Breaker Feedback
—Feature Enable
Utility Commanded Islanding with Open Transition Return:
In this mode, the
utility has control of the opening and closing of the island circuit breaker. When an island
is detected, the utility commands the island circuit breaker open. When the PureWave
SMS-250 system sees a UDM overvoltage or a UDM undervoltage, or an overfrequency
or underfrequency, and the Start Island SCADA control point is set, the PureWave SMS-
250 system will move to the
Island
mode. When the utility voltage and frequency return
to normal, the utility issues the Stop Island SCADA control point. When the SCADA
status point for the
Island Run
state is clear, the utility can command the island circuit
breaker closed.
For this mode, the user must use the
Configuration—Field Parameters
HMI screen
and configure the following:
Islanding Enable
—Feature Enabled
Utility Voltage Feedback
—Feature Enabled
Island Breaker Feedback
—Feature Enable
Island Run Test Modes
The following modes can be used to test the automatic islanding capability of the
PureWave SMS-250 without the disturbance:
HMI Commanded Islanding:
In this mode, the PureWave SMS-250 is in local mode
and will receive a Start Island command. When the island circuit breaker feedback volt-
age (24 V) goes away, indicating that the island circuit breaker is open, the PureWave
SMS-250 system will run in the
Island
mode providing power to the islanded load. When
the
Stop Island
command is received and the utility is providing power at a normal
voltage and frequency, the PureWave SMS-250 system will synchronize to the utility and
command the island circuit breaker closed. When the island circuit breaker feedback
voltage (24 V) returns, indicating that the island circuit breaker is closed, the PureWave
SMS-250 system will stop islanding.
Operation
