Differences

This shows you the differences between two versions of the page.

--- multiplus_faq [2018-12-17 21:39] – [Generator Sizing] guy_stewart
+++ multiplus_faq [2019-04-07 03:49] – guy_stewart
@@ Line 26: / Line 26: @@
 It is possible to overload generators with the power demanded by the Multi's charger. The following generator sizings are indicative of those sizes are appropriate for the charging potential of the various multis. It is still possible to overload these generator sizings with large loads, and flat batteries using the PowerAssist function, so they should be treated as safe minimums to eliminate this as a potential cause of issues. A bigger generator is usually better.
-^ Inverter/Charger Size ^ Recommended Generator Size ^ 240V AC Input Current Limit ^
+^ Inverter Charger Size ^ Minimum Recommended Generator Size ^ 240V AC Input Current Limit ^
 | 800VA | 2 kVa | 5A |
 | 1200VA | 2.5 kVa | 7A |
@@ Line 82: / Line 82: @@
 **AC low disconnect:** low limit: below this value, the MultiPlus will disconnect (default = 180Vac).
-On generators where the output voltage drops under load, setting this value to a higher value can help solve shutdowns on overload.
+On generators where the output voltage drops under load, setting this value to a higher value can help resolve inverter overload shutdowns.
-**AC Low connect:** minimum value: at this value or any higher value, the MultiPlus will reconnect after having disconnected (default = 187Vac).
+The reason this happens is that the Multi will synchronise and follow the generator voltage as it sags.
+If the generator is disconnected under load (either due to low-voltage disconnection, stalling, lack of fuel, etc) then when the Multi switches back to inverter mode; it must immediately supply all the power required by the loads at that same low voltage (and subsequent higher current).
+As overload is driven by current, not power, this can result in an overload.
+By increasing this minimum voltage level, you tell the inverter/charger switch to inverter mode sooner, at higher voltage and thus lower AC current, and potentially prevent the overload from occurring.
+**AC Low connect:** minimum value: at this value or any higher value, the MultiPlus will reconnect after having disconnected (default = 187Vac).
 ===== 1.4 Maximum voltage levels =====
@@ Line 99: / Line 106: @@
 For Full information on Loss of Mains detection, please see [[ve.bus:grid-codes-and-loss-of-mains-detection|this more detailed explanation.]]
-==== What is LOM detection? ====
-LOM is an automatic process that detects a change and loss of the generator/grid supply. After the detection, the inverter/charger will open its back-feed relay, making sure there is no live AC voltage on its AC-inputs, and anything connected to these inputs.
-==== Why is LOM detection required? ====
-The purpose of LOM is to detect that the Multi is no longer connected to the mains. Be that a generator or the grid. In such case, the Multi needs to open its back-feed relay. Not doing that would be unsafe.
-==== 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 mains generator/grid supply, 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.
-When connected to a generator, 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.
-==== LOM detection Type A and Type B ====
-LOM detection comes in two flavours: **Type A** and **Type B**.
-**Type A** is the strongest form LOM detection, which results 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.
-**Type B** has a more soft approach. Resulting in a slightly longer detection time. Still acceptable in several countries (South-Africa, and probably, though not tested and certified yet, also Germany). On generators, and also connection with a relatively high impedance mains connection, **Type B** will work better than **Type A**.
-For generators on which also **Type B** does not work, see Disabling LOM.
-==== Disabling LOM ====
-Besides choosing Type A and B, it is also possible to disable the LOM entirely.
-Note disabling the LOM on an input connected to the grid is only allowed when other external safety equipment is installed.
-Disabling the LOM on an input connected to generator can be done, but then other methods / warning signs must be provided. Ensuring that any installer that will work on the generator will make sure to also switch off or otherwise disconnect the Inverter/charger system.
-{{ :ve.bus:grid_code_compliant.png?direct |}}
 ===== Example configuration in VEConfigure =====
@@ Line 139: / Line 114: @@
 {{ :ve.bus:grid-code.png?direct |}}
-===== Questions =====
-==== Q1: Where can I get the password? ====
-A: From your dealer.
-==== Q2: Can I use ESS in a vehicle or a boat? ====
-A: No you cannot. After unplugging the shore cord it can take up to a few seconds for the system to detect the loss of mains and open the back-feed relay. During those seconds, the shore power plug will be `live`: there is 230 Volts AC on the terminals. The exact number of seconds differs per country and depends on the local requirements.
-The same applies to other solution where the wiring is not protected against accidental removing, for example a simple cable with end-user removable plug, such as a portable power supply.
-==== Q3: Can I use ESS with a generator? ====
-A: Yes you can. Note that the only installation type where that makes sense is a land based installation (no boat, and no vehicle). A Quattro must be used with AC input 1 connected to the generator, and AC input 2 connected to the grid. The role of the generator will be to provide power during a long grid failure.
-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.
-==== 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.
@@ Line 202: / Line 157: @@
 {{:veconfigure:charger_tab.jpg?nolink&400|}}
-**Derating of the power factor**
+===== 3.1 Derating of the power factor =====
 Some generators have a waveform which makes it difficult to charge with the normal charge mechanism. Through activating the "**Weak AC input**" function, another mechanism is used which will enable the MultiPlus to charge under practically any condition.
@@ Line 214: / Line 169: @@
 A detailed description of all settings is available in the VE-Configure help menu, and more instructions are available in our manuals.
+====== 4. In the “Inverter” tab of VE-Configure: ======
+===== 4.1 PowerAssist =====
+The [[https://www.victronenergy.com/upload/documents/White-paper-Achieving-the-impossible-EN.pdf|PowerAssist feature]] can be extremely useful, however it restricts the minimum AC input current limit and this may exceed your generators ability to supply. The [[https://www.victronenergy.com/blog/2018/04/20/multiplus-quattro-inverter-chargers-improved-current-limits/|exact restriction varies between models - see here for the list.]]
+If you have a small generator and have trouble getting connected or staying connected, Disable PowerAssist to allow the device to reduce the AC input current limit.
+====== Still not connecting? ======
+If the unit is still not connecting, switch the Multi over to Charger only mode.
+Try with a different generator.
+There can be issues with generators with Residual Current Devices (RCD's), control electronics or circuit breakers. There is some discussion about troubleshooting these issues on this [[https://community.victronenergy.com/questions/1702/multiplus-with-generator-and-residual-current-devi.html|Victron Community Question - Multiplus With Generator And Residual Current Device]], however as troubleshooting and correcting these faults have serious safety implications, they are best discussed with a local installer who has appropriate electrical qualifications, or your Victron Dealer.
+If there is still no connection, contact your dealer or distributor. Tell them the steps that you have taken already to attempt to get it to work and they can help from there.
@@ Line 227: / Line 203: @@
 [[https://community.victronenergy.com/topics/generator.html|Victron Community Questions and Answers about generators.]]
+[[https://www.victronenergy.com/upload/documents/Honda%20white%20paper%20GB.pdf|Victron Inverter/Chargers and Honda Generators]]
-===== Disqus =====
+===== DISQUS =====
 ~~DISQUS~~