ADDENDUM

Over/Under Voltage Fluctuations

VOLTAGE

MAXIMUM TRIP TIME*

 

 

Voltage < 60 V (< 50%)

6 cycles

 

 

Voltages between 60–106 V (50–88%)

120 cycles

 

 

Voltages between 106–132 V (88–110%)

Normal operation

 

 

Voltages between 132–165 V (110–137%)

120 cycles

 

 

Voltage >165 V (137%)

2 cycles

 

 

FREQUENCY

MAXIMUM TRIP TIME*

 

 

Frequency < 59.3 Hz

6 cycles

 

 

Frequency > 60.5 Hz

6 cycles

 

 

976-0013-D-002

*“Trip time” refers to the time between the abnormal conditions being applied and the inverter ceasing to energize the utility line.

Over/Under Frequency Disturbances

Small renewable energy systems are allowed to sell within a fixed frequency range of -0.7 Hz/ +0.5 Hz of the nominal frequency in which they will operate. When the utility frequency is outside the range of the nominal frequency window, the inverter must cease to energize the utility line within 6 cycles.

Reconnect Delay After a Utility Disturbance

An unacceptable utility event causes the renewable energy system to disconnect from the utility line. It will remain disabled until acceptable voltage and frequency have been maintained for a minimum of five minutes. After the 5 minute timer is complete, the inverter is allowed to automatically reconnect the renewable energy system to the utility.

Islanding Protection

The non-islanding inverter protection features required by UL1741 ensures that the inverter ceases to energize the utility line when the inverter is subjected to island conditions. As a result, active control techniques have been incorporated into the SW inverter for detecting potential dispersed-generation islands.

Autility wishing to ensure against renewable-energy supported dispersed-generation islanding may require the use of a non-islanding inverter. Trace™ has designed the new software protection system to comply with the requirements of the non-islanding inverter section of UL1741.

Over-current Protection

The Trace™ SW Series inverters also include over-current protection for the inverter system. This protective system is used if the inverter attempts to power too large of a load or if the inverter loses synchronization with the utility grid. This protective system is implemented with redundant systems in analog hardware, microprocessor software and with a mechanical device (circuit breaker). This insures the inverter is protected from damage and can not create an unsafe fault condition to the utility or residence.

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