Differences

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--- ve.bus:ve.bus_error_codes [2019-02-11 14:09] – [Error 11 - Relay Test Fault - Installation error or possibly relay failure] mvader
+++ ve.bus:ve.bus_error_codes [2019-02-14 20:45] – [Error 24 - Sw simonhackett
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 It shows:
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 ==== Error 24 - Switch-over system protection initiated ====
 There is a back-feed (or 'anti-islanding') relay present on the AC input of each unit. This relay is automatically opened during periods of AC input loss (e.g. grid or generator failure) as a safety mechanism to avoid the back-feeding of AC energy 'upstream'.
-Error 24 is raised when a Multi or Quattro detects current flowing through a back-feed relay during a period when the relay should be open - which means that the relay did not open when it should.
+Error 24 is raised when a Multi or Quattro detects current flowing through the back-feed relay during a period when the relay should be open - which means that the relay did not open when it should.
 This should not occur in a correctly installed and sized system. Possible causes in order of probability:
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   - There is too much AC load connected at the moment the relay needs to switch off. This large current will prevent the relay contacts from opening.\\ \\ Solution: remove excessive load. \\ \\
   - The AC input voltage slowly drops before it is being rejected by the Multis. Typically happens in installations with a genset. Especially when combined with AC loads that increase their current draw when the AC voltage drops: at the moment the Multis or Quattros decide to switch off, the current through the relays is too high to open them.\\ \\ Solution: Make the Multis or Quattros disconnect earlier: increase lower limit of AC input voltage in VEConfigure3. For example to 210 VAC. The factory setting is 180 VAC. \\ \\
-  - The back-feed relay has a hardware failure (and is stuck 'on')\\ \\ Solution: Replace faulty unit.
+  - The back-feed relay has a hardware failure \\ \\ Solution: Replace faulty unit.
-__Diagnostic notes for multi-unit clusters showing error 24__
+__Diagnostic notes for systems showing error 24 where a stuck 'on' relay is suspected__
-With all Multis or Quattros set to 'off' on their front panel rocker switches and with AC power presented to the input of the system, there should be no AC present on the AC-1 output terminals.
+In a single phase installation with two or more devices in parallel, or a three-phase installation with six or more devices, it can be difficult to identify the unit that is faulty because all units in at the relevant group of units will raise 'Error 24'.
-If AC //is// present on the output side while the units are switched off, this energy is flowing via the stuck back-feed relay. AC is also being back-fed into the inverter output circuitry as a result, and this may result in all units audibly 'humming' (even though they are set to be 'off').
+This happens because the faulty unit will be (incorrectly) supplying AC energy on it output at times when it should not be - including when its front panel rocker switch is set to 'off', When energy from the faulty unit's AC output flows in to the other unit(s) via their AC outputs, this causes these other units to be (incorrectly) flagged for 'Error 24' by the system self-test. The units concerned may also be 'buzzing' in the presence of AC power at their inputs with their rocker switches set 'off'.
-In a parallel-wired cluster, one faulty relay will make it appear that all units wired in parallel are faulty. To determine which unit is really at fault, power the cluster down and un-wire all AC inputs and all AC outputs. Then apply DC battery power and configure each unit into standalone mode so that it starts to invert and present power to its AC output. Any unit where there is //also// AC energy present on the //input// terminals has a stuck back-feed relay and needs to be replaced.
+To help identify which unit is faulty in this scenario, first un-wire the AC outputs of all the units concerned to prevent cross-feeding of AC energy via the AC outputs. Then apply AC power with all units still set to 'off' on their front panel rocker switches. Measure the AC output terminals with a meter - the faulty unit is the one that is still presenting AC voltage on its output terminals. If this approach is not successful, try turn turning the units 'On' and look for which unit now presents 'Error 24' in isolation.
+If this is not conclusive, try completely disconnecting all suspect units from all AC and DC sources. With an ohm-meter, measure the resistance between the neutral terminals on AC input and the AC output, A working unit will show no connection between these terminals. A faulty unit may show a connection to be present between these terminals, with either zero resistance or potentially with a small a non-zero (and non-normal) resistance present.
 ==== Error 25 - Firmware incompatibility ====