Rapid shutdown mode misconfiguration

ID: fm:rapid-shutdown-signal-misconfiguration
IRI: https://solarlattice.org/kb/fm/rapid-shutdown-signal-misconfiguration
Status: active
Also known as: SunSpec Shutdown not selected, Rapid Shutdown Mode not set, keep-alive signal not enabled, non-approved SunSpec shutdown device, Rapid shutdown signal misconfiguration

This fault happens when the inverter's rapid shutdown operating mode does not match the DC disconnection equipment installed on the PV modules or strings. If the array has an additional DC disconnection unit, the rapid shutdown function must be enabled, using the mode that fits that unit. Use On for a separate DC disconnection unit between the inverter and the array, and SunSpec Shutdown for devices that follow the SunSpec specification. Off disables the function. On inverters that offer TS4 Shutdown, TS4-R-F devices are not covered by that mode and need SunSpec Shutdown instead. To confirm the fault, read the Rapid Shutdown Mode and Rapid Shutdown Initiator parameters. If the initiator is set to digital input, check that an initiator is actually wired to that input. To fix it, change the parameter to the correct mode, and use only rapid shutdown devices on the manufacturer's compatibility list. With SunSpec rapid shutdown devices installed, I-V curves can show steps and kinks even when the array is healthy, so do not read those features as a module fault.

<!-- review notes

sentence 1: support check: partial - Mode must be selected in accordance with the disconnection unit used, but passages don't describe a fault occurring on mismatch.
sentence 5: support check: partial - Parameters and the requirement to connect an initiator to GSI are stated, but not a confirmation procedure for a fault.
sentence 6: support check: partial - Setting the mode parameter and a compatibility list are mentioned, but not that only listed devices should be used as a fix.
sentence 1: review: partial - The passages say the mode must be chosen to match the DC disconnection unit, but they never describe a mismatch as a fault that happens. -->

Claims

`affects`

c1 drafted · lead Inverter

The rapid shutdown operating mode is an inverter parameter (On, SunSpec Shutdown, Off, and TS4 Shutdown on some models).

sbx1xpus41-configuring-the-rapid-shutdown-function sec=h1 h=7b6c37b20ba8
sbx1xpus41-configuring-the-rapid-shutdown-function tbl=1 h=6ac3c561834b
stpxx-us-41-configuring-the-rapid-shutdown-function tbl=1 h=86d85195c286

c2 drafted · lead Module-level rapid shutdown device

The mode must match the DC disconnection unit fitted to the modules or strings. With TS4-R-F devices, SunSpec Shutdown is the required mode.

sbx1xpus41-configuring-the-rapid-shutdown-function sec=h1 h=7b6c37b20ba8
STPxx-US-41-IV-Curve-TI-en-11 sec=h6 h=20f41afb0134
sbx1xpus41-configuring-the-rapid-shutdown-function tbl=1.r4 h=b399418e132b

c3 drafted · lead Rapid shutdown initiator

A separate parameter chooses the initiator, either the AC disconnect or a digital input. If digital input is chosen, an initiator must be wired to the GSI input.

sbsexx-us-50-parameters-for-rapid-shutdown-function-us sec=h1 h=7814e82efeb1
SBSExx-US-50-BE-en-11 sec=8.8 h=5f4090d18a43

`caused_by`

c4 drafted · lead Inverter parameter settings

Choosing a mode that does not match the installed DC disconnection unit, or leaving the function Off when such a unit is present.

sbx1xpus41-configuring-the-rapid-shutdown-function sec=h1 h=7b6c37b20ba8
sbx1xpus41-configuring-the-rapid-shutdown-function tbl=1 h=6ac3c561834b
sbx1xpus41-configuring-the-rapid-shutdown-function tbl=1.r4 h=b399418e132b

review note: support check: partial - Modes must match the DC disconnection unit and Off disables the function, but the passages don't explicitly describe mismatch or leaving Off as a misconfiguration.

`detected_by`

c5 drafted · lead Inverter settings review

Check the Rapid Shutdown Mode parameter (Operation.RSSOpMode) and the Rapid Shutdown Initiator parameter (Operation.RSSInitiator).

sbsexx-us-50-parameters-for-rapid-shutdown-function-us sec=h1 h=7814e82efeb1
SBSExx-US-50-BE-en-11 tbl=30 h=f00aac9410b1
sbsexx-us-50-parameters-for-rapid-shutdown-function-us tbl=1 h=4cb1e58072b1

review note: support check: partial - The parameters Operation.RSSOpMode and RSSInitiator are listed, but nothing states that reviewing them is a detection method.

`mitigated_by`

c6 drafted · lead Inverter parameter adjustment

Set the mode to suit the disconnection unit: On for a separate DC disconnection unit, SunSpec Shutdown for SunSpec-compliant devices.

sbx1xpus41-configuring-the-rapid-shutdown-function sec=h1 h=7b6c37b20ba8
STPTL-US-10-IA-xx-22 sec=h165 h=071194e91e49
SBxx-US-1XP-40-BA-en-13 sec=h139 h=071194e91e49
sbx1xpus41-configuring-the-rapid-shutdown-function tbl=1 h=6ac3c561834b

c7 drafted · lead Certified product selection

Use rapid shutdown devices that appear on the manufacturer's list of compatible SunSpec-certified devices.

STPxx-US-41-IV-Curve-TI-en-11 sec=h6 h=20f41afb0134
STPxx-US-50-BE-en-14 tbl=9.r3 h=85de59eb1b35

review note: support check: partial - A list of compatible SunSpec rapid shutdown devices exists, but passages don't say using listed devices mitigates mode misconfiguration.

Referenced by

Rapid shutdown device failure distinguished_from c17

Rapid shutdown mode misconfiguration

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