The question about the RD2624E might be software. Software version 4.2 had the high Vac input at 260 Vac. In 2011 Magnum changed to V5.4 which raised the high Vac input to 275 Vac. For some reason the RD2624E was the only unit with the lower Vac input setting. Once the “High Vac Fault” is registered AC has to be removed before it will reset. So in this case the voltage probably did hit 260 Vac and registered the fault but when it was measured it was lower but would not reset until ac is removed and reapplied to the unit.
For the MS4348PE inverters, did the UPS mode fix the problem? I believe the 110vac readings are a result of some of the meters not being updated by Magnum – they are still displaying the US voltage numbers instead of the European or 230vac numbers.
If the servers are still shutting off on UPS mode, then you might have some of those new servers with the cheap power supplies that have hardly any capacitors in them. They cannot tolerate much of a break in power. You might try either putting a UPS in between the inverter and server or possibly changing inverters – the Xantrex XW claims a shorter transfer time, but not sure it is true. Very hard to measure.
On the MS4348PAE I would check the “Threshold Setting” in the ME-RTR. If you set the threshold lower or OFF the Slave will respond faster to help the Master run loads.
To Change the Threshold setting:
1. Push the SETUP button
2. #2 Inverter SETUP
3. 02E Parallel Threshold
The default setting is 60% which means that the Master must exceed 60% capacity or 2580 watts (4300 x .60 = 2580 watts) before the Slave turns ON. If you lower this setting to 30% then the Slave will turn on at 1290 watts (4300 x .30 = 1290 watts). If you set the Parallel Threshold to OFF then the Slave will always be ON, the settings are in 10% increments. This settings is the same for ALL Slave inverters so if there were 1-Master and 3-Slave inverters in a system ALL the Slave inverters would come on at the Parallel Threshold setting. After approximately 2 minutes any Slave would turn OFF if the combined load is less than the Master plus needed Slaves.
Yes, if the Support Mode is selected.
If Support Mode is active and ac loads exceeds the input current set point the inverter will
- back off on charging
- reduce the charge rate to zero
- draw current from the batteries to support loads
The above actions are load dependent.
If Support mode is active it interacts with any Ac source be it grid or generator.
Because it can be used with grid or generator it is labeled INPUT SUPPORT.
The target used to trigger Support Mode is the ac input amps setting.
A couple of clarifications, offset is not a settable mode. It is a feature built into the inverter. Offset operates on 4 voltages, Absorb, Float, Equalize and the Sell RE set points. How it operates depends on the individual voltage set points between devices (inverters and FM charge controllers). Let’s consider a typical charging set point for an AGM battery. Typical Absorb value could vary from 57.6 to 59.6. If the inverter is set to 57.6 and the charge controllers (or external source) are set to 59.6. During a bulk cycle both sources will contribute to the charge of the battery. Once the inverters absorb value is reached 57.7 current flow into the battery is reduced. If the FM units have sufficient energy and attempt to reach their Absorb value of 59.6, charging from the grid is reduced to zero as long as its absorb value is maintained. Not only will charging from the inverter be reduced (possibly to zero). The inverter will do everything possible to maintain its absorb set point. If grid tied it will use excess pv to run the loads or even sell back to the grid. The inverter job is to maintain its voltage target be it the Absorb, Float, Equalize or the Sell Re set point. If a cloud passes by and solar harvest is reduced the inverter will use the grid to maintain the target voltage.
As with all our inverters the incoming ac is used to run the loads and provide charging.
What happens next depends on the voltage set points of the individual devices.
If the charge controllers set point is above the inverters set point and the inverters setpoint is maintained any additional PV power will be used to power the loads.
As with all our inverters the incoming ac is used to run the loads and provide charging.The idea is to use PV or renewable source first and use the grid as a last resort. Offset uses the Absorb, Float, Eq and sell Re points as the targets.
This is a good question and most people are probably heavily influenced by what they have in stock, just as you say. There is not an firm rule, but anything over about 150 amps of current is a good candidate to move up to the next available voltage. This would imply a break-out of about 1800w as the limit for 12v, 3,600w for 24v and so on. Most inverter manufacturers follow close to that line, although Magnum has some high current units like the MS2712E (225 amps) which is mostly aimed at the RV/caravan markets where the coach battery bank is 12v.
The main thing is to get the cable sizing and breakers/fuses correct – check the wire sizing chart and overcurrent protection charts on our site.
In a perfect world, we would work at very high voltages – this would reduce power loss due to heat, allow smaller cable sizes, and put less stress on the weak parts of the battery cabling (like terminal connections). But the solar industry was built around automotive battery standards, so we are all working in sets of 12v at the moment. There are more and more inverters and charge controllers available at higher voltages now, but because of our batteries, those are still only practical for fairly large systems. As the battery industry changes, we might see different voltages for storage, which would allow changes in all of the other components.