The inverter has three under-frequency (UF) and three over-frequency (OF) trip points and
times, as well as one under-frequency instantaneous trip point and one over-frequency
instantaneous trip point. These parameters are configurable to the ranges listed
below:
Table 1. Inverter Frequency Trip Points
| Parameter |
Voltage Range |
Default Values (p.u.) |
Time (s) |
| LFRT Point 1 |
240V/208V |
95.5 |
2 |
| LFRT Point 2 |
240V/208V |
57 |
0.13 |
| LFRT Point 3 |
240V/208V |
57 |
0.13 |
| HFRT Point 1 |
240V/208V |
60.5 |
2 |
| HFRT Point 2 |
240V/208V |
62 |
0.13 |
| HFRT Point 3 |
240V/208V |
62 |
0.13 |
The Frequency Ride-Through (FQRT) settings are pre-programmed in the inverter to comply
with IEEE 1547 requirements as per the defaults below:
Table 2. Inverter FQRT Default Settings
| Function |
Frequency (Hz) |
Clearing Time (s) |
| UF1 |
< 57 |
0.16 |
| UF2 |
< 59.5 |
2 |
| OF1 |
> 60.5 |
2 |
| OF2 |
> 62 |
0.16 |
Table 3. Inverter FQRT Default Settings
| Operating Region |
Frequency at Point of Interconnection |
Operating Mode |
Ride-Through Until (s) |
Default Maximum Trip Time (s) |
Range of Adjustability Frequency |
Range of Adjustability Clearing Time (s) |
| OF2 |
f>64.0 |
Permissive Operation |
None |
0.16 |
62.0-66.0 |
0.16-1,000 |
| f>65.0 [L+M] |
| OF1 |
64.0≥f>63.0 |
Mandatory Operation (Freq-watt) |
20 |
21 |
61.0-66.0 |
21-1,000 |
| 65.0≥f>63.0[L+M] |
| NOF |
63.0≥f>60.0 |
Continuous Operation (Freq-Watt) |
Indefinite |
N/A |
N/A |
N/A |
| NUF |
60.0>f≥57.0 |
Continuous Operation |
Indefinite |
N/A |
N/A |
N/A |
| UF1 |
57.0>f≥56.0 |
Mandatory Operation |
20 |
21 |
50.0-59.0 |
21-1,000 |
| 57.0>f≥50.0[L+M] |
| UF2 |
56.0>f |
Permissive Operation |
None |
0.16 |
50.0-57.0 |
0.16-1,000 |
| 50.0>f[L+M] |