Differences

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--- ve.bus:grid-codes-and-loss-of-mains-detection [2018-08-22 12:43] – [LOM detection Type A and Type B] pba
+++ ve.bus:grid-codes-and-loss-of-mains-detection [2020-07-20 16:48] – [LOM detection Type A and Type B] mvader
@@ Line 20: / Line 20: @@
 ==== How does LOM detection relate to overload shutdowns? ====
-To detect a loss of mains, the inverter/charger will constantly try to shift the AC frequency. When connected to a stable grid, with a normal accepted impedance, it will not be possible to do so, and it can therefor detect that the mains is still present. In case the mains was lost, the inverter/charger will be able to shift the frequency at will, without any resulting correction currents.
+To detect a loss of mains, the inverter/charger will constantly try to shift the AC frequency. When connected to a stable grid, with a normal accepted impedance, it will not be possible to do so, and it can therefore detect that the mains is still present. In case the mains was lost, the inverter/charger will be able to shift the frequency at will, without any resulting correction currents.
 When connected to a generator, or to a grid with a long extension cable or long ‘last mile’ cable, the pushing and pulling on the grid does create high currents, and as a result the inverter/charger algorithm can become unstable and switch itself off in overload.
+==== How does LOM detection relate to passthru? ====
+Similar to above section about overload, a too weak connection to the utility can cause continuous increases and decreases in frequency, not resulting in overload but still resulting in continuous shifts in frequency.
+This (can) cause a safety mechanism to activate which temporarily disables feed-in.
+==== How to identify if LOM detection causes issues? ====
+By temporarily disabling the LOM, one can identify that the LOM is causing an issue. Here is how to disable it:
+Open VEConfigure, and then on the Grid tab, change LOM detection setting to None. This requires a password, contact your dealer.
+Save the settings, and wait to see if this helps. In case it does help, see next section.
+NOTE: for LOM to cause issues is really rare. Its documented in detail on this page to help installations where it does cause an issue, but its really rather rare to happen in the first place. Do make sure to read the [[ess:design-installation-manual|ESS manual, and especially its FAQ chapter]], for other common causes of issues when troubleshooting.
+==== What to do when LOM detection causes issues? ====
+The previous section explains how to identify if LOM causes an issue. It can cause overload shutdowns, and it can also cause a system to frequently show "Passthru" as a state. Mostly related to a high impedance connection to the utility.
+The solution is then to make for a better connection to the utility - but as that is often quite hard to achieve, here is another solution: keep LOM disabled and install an external anti-islanding safety devices (ENS). For example from Ziehl, or another brand. Make sure to comply to local rules & regulations - this is a real critical safety issue.
 ==== LOM detection Type A and Type B ====
-LOM detection comes in two flavours: **Type A** and **Type B**.
+Within the Victron product range, there are two types of LOM detection available **Type A** and **Type B**.
+All recent certified grid codes use Type B. On the MultiPlus-II models, **all** grid codes use Type B, and Type B is no longer used.
 **Type A** is the strongest form of LOM detection resulting in the quickest detection time. It requires a low impedance connection to the grid (short, well sized cables). LOM **Type A** will not work with generators.
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 Some, bigger or better quality generators, will be able to work with LOM **Type B**. For other less stable generators it will be required to disable LOM entirely. In that case make the installation such that it is still safe: no simple extensions cords, use enclosed wiring cabinets with warnings on the outside and/or an external ENS.
+More information here: https://www.victronenergy.com/live/multiplus_faq
 ==== Q4: I use ESS, but have disabled feed-back, is a grid-code still required? ====
 A: Yes, also in this case LOM is required to make for a safe and also local regulations compliant system. Running ESS with disabled-feed-back is still not the same as using a Multi in its default configuration without ESS.
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