Frequency trip

ID: func:frequency-trip
IRI: https://solarlattice.org/kb/func/frequency-trip
Status: active
Also known as: frequency protection, over/under-frequency trip, PTOF, PTUF, Grid Frequency Protection, Shall Trip Function, Frequency Trip Settings, Grid Over Frequency Protection, Grid Low Frequency Protection
Category: Protection
Function kind: protection

Frequency trip disconnects the inverter from the grid when grid frequency stays above an over-frequency limit or below an under-frequency limit for longer than its set clearing time. Settings normally come in two stages per direction, such as OF1/OF2 and UF1/UF2, each with its own frequency and clearing time; utilities like PPL EU and ISO New England publish their own required values. CPS string inverters expose GridFrqMax1-3, GridFrqMin1-3 and matching trip time parameters, with separate defaults for the IEEE 1547-2018, Rule 21 and ISO-NE profiles. The Fronius Galvo states a frequency trip accuracy of 0.05 Hz and has a settable tolerance time for frequency limit violations. On Solis hybrids running from a generator, the HF1/HF2 and LF1/LF2 trip points can be widened to stop nuisance trips, but only in backup or off-grid mode, and they must be set back when the grid returns.

<!-- review notes

sentence 1: support check: partial - Passages say the inverter disconnects after a programmed delay, but the u36 text ties disconnect to abnormal voltage, and the clearing-time tables don't state the general mechanism fully.
sentence 2: support check: partial - Two stages per direction and PPL EU/ISO-NE values are shown, but 'normally' and that utilities publish their own required values (ISO-NE settings are SolarEdge settings) aren't stated.
sentence 3: support check: partial - Parameters and profile defaults shown, but a single product doesn't show all of GridFrqMin1-3 in u30, and some tables only have IEEE/Rule21; mostly supported across passages.
sentence 1: review: partial - The IEEE trip tables give frequency limits with clearing times, and ABB says the inverter disconnects after a programmed delay, but no passage states the general rule that the inverter trips when frequency stays past the limit for longer than… -->

Claims

`default_value`

c1 drafted · lead nominal 56.5 HZ

Scope: standard IEEE 1547-2018 proposed

Conditions: UF2 shall-trip default frequency

IEEE 1547 - 2018 [code/standard] tbl=25.r4 h=3614858a0cd9

review note: possible conflict with c4 (same source; check the conditions)

c3 drafted · lead nominal 0.16 SEC

Scope: standard IEEE 1547-2018 proposed

Conditions: UF2 default clearing time

IEEE 1547 - 2018 [code/standard] tbl=25.r4 h=3614858a0cd9

c4 verified · fact nominal 62 HZ

Scope: standard IEEE 1547-2018 proposed

Conditions: OF2 shall-trip default frequency

IEEE 1547 - 2018 [code/standard] tbl=25.r1 h=50c2daaa9bd2

verified by: review-workflowverified on: 2026-10-24review note: possible conflict with c1 (same source; check the conditions)

c6 drafted · lead nominal 0.16 SEC

Scope: standard IEEE 1547-2018 proposed

Conditions: OF2 default clearing time

IEEE 1547 - 2018 [code/standard] tbl=25.r1 h=50c2daaa9bd2

c31 drafted · lead nominal 61.2 HZ

Scope: products CPS SCA25KTL-DO/US-208, CPS SCA36KTL-DO/US-480, CPS SCA50-60KTL-DO/US-480

Conditions: CPS GridFrqMax1, IEEE 1547-2018 and ISO-NE profiles

CPS SCA25KTL-DO-US-208 User Manual Rev 1.2 tbl=26 h=1c2bb196b629
CPS-SCA36-50-60KTL-DOUS-480-User-Manual-Rev-4.0 tbl=31 h=45dcc2011c57
CPS-SCA36-50-60KTL ops tbl=7 h=45dcc2011c57

c32 drafted · lead nominal 60.5 HZ

Scope: products CPS SCA25KTL-DO/US-208, CPS SCA36KTL-DO/US-480, CPS SCA50-60KTL-DO/US-480; standard CA Rule 21 proposed

Conditions: CPS GridFrqMax1, Rule 21 profile

CPS SCA25KTL-DO-US-208 User Manual Rev 1.2 tbl=26 h=1c2bb196b629
CPS-SCA36-50-60KTL-DOUS-480-User-Manual-Rev-4.0 tbl=31 h=45dcc2011c57
CPS-SCA36-50-60KTL ops tbl=7 h=45dcc2011c57

review note: possible conflict with c35 (same source; check the conditions)

c35 verified · fact nominal 57 HZ

Scope: products CPS SCA25KTL-DO/US-208, CPS SCA36KTL-DO/US-480, CPS SCA50-60KTL-DO/US-480; standard CA Rule 21 proposed

Conditions: CPS GridFrqMin2 and GridFrqMin3, Rule 21 profile (56.5 Hz for IEEE 1547-2018 and ISO-NE)

CPS SCA25KTL-DO-US-208 User Manual Rev 1.2 tbl=26 h=1c2bb196b629
CPS-SCA36-50-60KTL-DOUS-480-User-Manual-Rev-4.0 tbl=31 h=45dcc2011c57
CPS-SCA36-50-60KTL ops tbl=7 h=45dcc2011c57

verified by: review-workflowverified on: 2026-10-24review note: possible conflict with c32 (same source; check the conditions)

`setting_range`

c2 verified · fact 50–57 HZ

Scope: standard IEEE 1547-2018 proposed

Conditions: UF2 allowable frequency setting range

IEEE 1547 - 2018 [code/standard] tbl=25.r4 h=3614858a0cd9

verified by: review-workflowverified on: 2026-10-24review note: possible conflict with c5 (same source; check the conditions)

c5 drafted · lead 61.8–66 HZ

Scope: standard IEEE 1547-2018 proposed

Conditions: OF2 allowable frequency setting range

IEEE 1547 - 2018 [code/standard] tbl=25.r1 h=50c2daaa9bd2

review note: possible conflict with c2 (same source; check the conditions)

c33 drafted · lead 60–66 HZ

Scope: products CPS SCA25KTL-DO/US-208, CPS SCA36KTL-DO/US-480, CPS SCA50-60KTL-DO/US-480

Conditions: CPS over-frequency thresholds GridFrqMax1-3, all profiles

CPS SCA25KTL-DO-US-208 User Manual Rev 1.2 tbl=26 h=1c2bb196b629
CPS-SCA36-50-60KTL-DOUS-480-User-Manual-Rev-4.0 tbl=31 h=45dcc2011c57
CPS-SCA36-50-60KTL ops tbl=7 h=45dcc2011c57

c34 drafted · lead 48–60 HZ

Scope: products CPS SCA25KTL-DO/US-208, CPS SCA36KTL-DO/US-480, CPS SCA50-60KTL-DO/US-480

Conditions: CPS under-frequency thresholds GridFrqMin1-3, all profiles

CPS SCA25KTL-DO-US-208 User Manual Rev 1.2 tbl=26 h=1c2bb196b629
CPS-SCA36-50-60KTL-DOUS-480-User-Manual-Rev-4.0 tbl=31 h=45dcc2011c57
CPS-SCA36-50-60KTL ops tbl=7 h=45dcc2011c57

c36 verified · fact 0–1000 SEC

Scope: products CPS SCA25KTL-DO/US-208, CPS SCA36KTL-DO/US-480, CPS SCA50-60KTL-DO/US-480

Conditions: CPS frequency trip times, IEEE 1547-2018 and ISO-NE profiles

CPS SCA25KTL-DO-US-208 User Manual Rev 1.2 tbl=26 h=1c2bb196b629
CPS-SCA36-50-60KTL-DOUS-480-User-Manual-Rev-4.0 tbl=31 h=45dcc2011c57
CPS-SCA36-50-60KTL ops tbl=7 h=45dcc2011c57

verified by: review-workflowverified on: 2026-10-24

c37 drafted · lead 0–655 SEC

Scope: products CPS SCA25KTL-DO/US-208, CPS SCA36KTL-DO/US-480, CPS SCA50-60KTL-DO/US-480; standard CA Rule 21 proposed

Conditions: CPS under-frequency trip times FrqMinTripT1-3, Rule 21 profile

CPS SCA25KTL-DO-US-208 User Manual Rev 1.2 tbl=26 h=1c2bb196b629
CPS-SCA36-50-60KTL-DOUS-480-User-Manual-Rev-4.0 tbl=31 h=45dcc2011c57
CPS-SCA36-50-60KTL ops tbl=7 h=45dcc2011c57

c38 verified · fact 0–1310 SEC

Scope: products CPS SCA100K-T-US-480 / SCA50K-T-US-208

Conditions: CPS frequency trip times (FrqMaxTripT1/T2/T3, FrqMinTripT1)

CPS SCA100K-T-US-480 SCA50K-T-US-208 User Manual Rev 1.0 tbl=43 h=281df4b8b471

verified by: review-workflowverified on: 2026-10-24

c39 verified · fact 0.016–600 SEC

Scope: products Fronius Galvo 208-240

Conditions: Fronius Galvo frequency limit violation tolerance time

Fronius Galvo 208-240 Operating Instructions 42_0410_1934 tbl=9.r6 h=2a74c7f7e2a4

verified by: review-workflowverified on: 2026-10-24

`trip_threshold`

c7 disputed nominal 58.5 HZ

Conditions: PPL EU required UF1 shall-trip setting

DER Ride Through Settings [code/standard] tbl=4 h=d45e5447a687

review note: possible conflict with c9 (same source; check the conditions); possible conflict with c11 (same source; check the conditions); possible conflict with c13 (same source; check the conditions)conflicts with: Frequency trip (c15)conflicts with: Frequency trip (c17)conflicts with: Frequency trip (c21)

c9 verified · fact nominal 56.5 HZ

Conditions: PPL EU required UF2 shall-trip setting

DER Ride Through Settings [code/standard] tbl=4 h=d45e5447a687

verified by: review-workflowverified on: 2026-10-24review note: possible conflict with c7 (same source; check the conditions); possible conflict with c11 (same source; check the conditions); possible conflict with c13 (same source; check the conditions); review: the compiler-flagged conflict (func:frequency-trip#c15, func:frequency-trip#c17, func:frequency-trip#c19) is a scenario difference, resolved at review

c11 disputed nominal 61.2 HZ

Conditions: PPL EU required OF1 shall-trip setting

DER Ride Through Settings [code/standard] tbl=5 h=356df394eec9

review note: possible conflict with c7 (same source; check the conditions); possible conflict with c9 (same source; check the conditions); possible conflict with c13 (same source; check the conditions)conflicts with: Frequency trip (c15)conflicts with: Frequency trip (c19)conflicts with: Frequency trip (c21)

c13 disputed nominal 62 HZ

Conditions: PPL EU required OF2 shall-trip setting

DER Ride Through Settings [code/standard] tbl=5 h=356df394eec9

review note: possible conflict with c7 (same source; check the conditions); possible conflict with c9 (same source; check the conditions); possible conflict with c11 (same source; check the conditions)conflicts with: Frequency trip (c17)conflicts with: Frequency trip (c19)conflicts with: Frequency trip (c21)

c15 disputed nominal 62 HZ

Conditions: Generac PWRmicro OF2 frequency trip

Generac PWRmicro installation manual A0008718926 tbl=20.r1 h=f3190f9274e9

review note: possible conflict with c17 (same source; check the conditions); possible conflict with c19 (same source; check the conditions); possible conflict with c21 (same source; check the conditions)conflicts with: Frequency trip (c7)conflicts with: Frequency trip (c9)conflicts with: Frequency trip (c11)

c17 disputed nominal 61.2 HZ

Conditions: Generac PWRmicro OF1 frequency trip

Generac PWRmicro installation manual A0008718926 tbl=20.r2 h=4df42ceedb23

review note: possible conflict with c15 (same source; check the conditions); possible conflict with c19 (same source; check the conditions); possible conflict with c21 (same source; check the conditions)conflicts with: Frequency trip (c7)conflicts with: Frequency trip (c9)conflicts with: Frequency trip (c13)

c19 disputed nominal 58.5 HZ

Conditions: Generac PWRmicro UF1 frequency trip

Generac PWRmicro installation manual A0008718926 tbl=20.r3 h=7ab836be4e7c

review note: possible conflict with c15 (same source; check the conditions); possible conflict with c17 (same source; check the conditions); possible conflict with c21 (same source; check the conditions)conflicts with: Frequency trip (c9)conflicts with: Frequency trip (c11)conflicts with: Frequency trip (c13)

c21 verified · fact nominal 56.5 HZ

Conditions: Generac PWRmicro UF2 frequency trip

Generac PWRmicro installation manual A0008718926 tbl=20.r4 h=aa2f35f33a37

verified by: review-workflowverified on: 2026-10-24review note: possible conflict with c15 (same source; check the conditions); possible conflict with c17 (same source; check the conditions); possible conflict with c19 (same source; check the conditions); review: the compiler-flagged conflict (func:frequency-trip#c7, func:frequency-trip#c11, func:frequency-trip#c13) is a scenario difference, resolved at review

c23 drafted · lead nominal 62 HZ

Scope: regions ISO New England market area proposed

Conditions: SolarEdge ISO New England setting FgMax1

iso new england configuration instructions na tbl=2.r1 h=1eda7a6cb10b

review note: possible conflict with c25 (same source; check the conditions); possible conflict with c27 (same source; check the conditions); possible conflict with c29 (same source; check the conditions)

c25 drafted · lead nominal 61.2 HZ

Scope: regions ISO New England market area proposed

Conditions: SolarEdge ISO New England setting FgMax2

iso new england configuration instructions na tbl=2.r2 h=b275a4627529

review note: possible conflict with c23 (same source; check the conditions); possible conflict with c27 (same source; check the conditions); possible conflict with c29 (same source; check the conditions)

c27 drafted · lead nominal 58.5 HZ

Scope: regions ISO New England market area proposed

Conditions: SolarEdge ISO New England setting FgMin1

iso new england configuration instructions na tbl=2.r3 h=9c4b323e6329

review note: possible conflict with c23 (same source; check the conditions); possible conflict with c25 (same source; check the conditions); possible conflict with c29 (same source; check the conditions)

c29 drafted · lead nominal 56.5 HZ

Scope: regions ISO New England market area proposed

Conditions: SolarEdge ISO New England setting FgMin2

iso new england configuration instructions na tbl=2.r4 h=bfcf8582de93

review note: possible conflict with c23 (same source; check the conditions); possible conflict with c25 (same source; check the conditions); possible conflict with c27 (same source; check the conditions)

`trip_time`

c8 disputed nominal 301 SEC

Conditions: PPL EU required UF1 clearing time

DER Ride Through Settings [code/standard] tbl=4 h=d45e5447a687

review note: possible conflict with c10 (same source; check the conditions); possible conflict with c14 (same source; check the conditions)conflicts with: Frequency trip (c16)conflicts with: Frequency trip (c18)conflicts with: Frequency trip (c20)conflicts with: Frequency trip (c22)

c10 disputed nominal 0.2 SEC

Conditions: PPL EU required UF2 clearing time

DER Ride Through Settings [code/standard] tbl=4 h=d45e5447a687

review note: possible conflict with c8 (same source; check the conditions); possible conflict with c12 (same source; check the conditions)conflicts with: Frequency trip (c16)conflicts with: Frequency trip (c18)conflicts with: Frequency trip (c20)conflicts with: Frequency trip (c22)

c12 verified · fact nominal 301 SEC

Conditions: PPL EU required OF1 clearing time

DER Ride Through Settings [code/standard] tbl=5 h=356df394eec9

verified by: review-workflowverified on: 2026-10-24review note: possible conflict with c10 (same source; check the conditions); possible conflict with c14 (same source; check the conditions); review: the compiler-flagged conflict (func:frequency-trip#c16, func:frequency-trip#c18, func:frequency-trip#c20, func:frequency-trip#c22) is a scenario difference, resolved at review

c14 disputed nominal 0.2 SEC

Conditions: PPL EU required OF2 clearing time

DER Ride Through Settings [code/standard] tbl=5 h=356df394eec9

c16 verified · fact nominal 0.16 SEC

Conditions: Generac PWRmicro OF2 clearing time

Generac PWRmicro installation manual A0008718926 tbl=20.r1 h=f3190f9274e9

verified by: review-workflowverified on: 2026-10-24review note: possible conflict with c18 (same source; check the conditions); possible conflict with c20 (same source; check the conditions); review: the compiler-flagged conflict (func:frequency-trip#c8, func:frequency-trip#c10, func:frequency-trip#c12, func:frequency-trip#c14) is a scenario difference, resolved at review

c18 verified · fact nominal 300 SEC

Conditions: Generac PWRmicro OF1 clearing time

Generac PWRmicro installation manual A0008718926 tbl=20.r2 h=4df42ceedb23

verified by: review-workflowverified on: 2026-10-24review note: possible conflict with c16 (same source; check the conditions); possible conflict with c22 (same source; check the conditions); review: the compiler-flagged conflict (func:frequency-trip#c8, func:frequency-trip#c10, func:frequency-trip#c12, func:frequency-trip#c14) is a scenario difference, resolved at review

c20 disputed nominal 300 SEC

Conditions: Generac PWRmicro UF1 clearing time

Generac PWRmicro installation manual A0008718926 tbl=20.r3 h=7ab836be4e7c

review note: possible conflict with c16 (same source; check the conditions); possible conflict with c22 (same source; check the conditions)conflicts with: Frequency trip (c8)conflicts with: Frequency trip (c10)conflicts with: Frequency trip (c12)conflicts with: Frequency trip (c14)

c22 verified · fact nominal 0.16 SEC

Conditions: Generac PWRmicro UF2 clearing time

Generac PWRmicro installation manual A0008718926 tbl=20.r4 h=aa2f35f33a37

c24 drafted · lead nominal 160 MilliSEC

Scope: regions ISO New England market area proposed

Conditions: SolarEdge ISO New England setting FgMax1 time

iso new england configuration instructions na tbl=2.r1 h=1eda7a6cb10b

review note: possible conflict with c26 (same source; check the conditions); possible conflict with c28 (same source; check the conditions)

c26 verified · fact nominal 300000 MilliSEC

Scope: regions ISO New England market area proposed

Conditions: SolarEdge ISO New England setting FgMax2 time

iso new england configuration instructions na tbl=2.r2 h=b275a4627529

verified by: review-workflowverified on: 2026-10-24review note: possible conflict with c24 (same source; check the conditions); possible conflict with c30 (same source; check the conditions)

c28 drafted · lead nominal 300000 MilliSEC

Scope: regions ISO New England market area proposed

Conditions: SolarEdge ISO New England setting FgMin1 time