There's new battery technology on the way, nano-based litium batteries, that exceed 10x the capacity of standard lithium batteries. If these can be mass-produced at comparable cost to existing lithium batteries, a Prius-sized (and prius-priced) battery would suddenly be an effective PHEV...
I'm inclined to agree with unclebob, except to add that it depends on which leg has voltage, and the added length of top/bottom core to travel through will mean that some legs may induce more than 25% voltage while some less. Would be in the area of 25% for each, though.
The heat-to-water dissipation is going to be much faster than heat-to-air-through-insulation. Honestly, I'd throw out the NEC tables and do calculations from scratch based on the resistance of the metal and heat dissipation. As already noted, you don't want your water boiling! Size them for...
Are these two 800A MCCBs feeding two inverters, or are they feeding the same 1600A inverter?
Parallel feeders like this are common in UPS applications where the device that's fed offers regulation of the current and parallel redundancy is standard practice. AFAIK, NEC prohibits straight-up...
Sudden loading of an unloaded generator will cause a momentary undervoltage/underfrequency as the governor adjusts the throttle. You need to ensure your settings aren't such that the underfrequency relay in the breaker trips open. By the same token, you don't want to set it too low, or it will...
If you're using 120V (Wye), you can simply add up the 1-phase line currents. But it works out the same either way you calculate it:
39,900VA/(208*1.73) = 39,900VA/(120*3) = 111A/phase.
This may be a good value for scoping, but if you know the actual load, it's best to use it instead.
The conductivity of earth may be low, but the cross-section is HUGE, so overall resistance is small- practically 0, with all the resistance centered around the ground rod and very little difference if it's 100km or 1000km. You really couldn't ask for a better conductor for long distances.
I recieved data from the manufacturer that ambient rise is 65°C for an 80°C rise enclosed transformer! If 115° and 150°C rise and hotter are common ratings for transformers, how in the world is this reconciled with 90°C rated cables?
Am I worried over nothing, will the cables wick away the...
The shut-down procedure for many large UPS systems involves bleeding the DC bus prior to shut-down. You generally secure the rectifier input and battery breakers, and watch the DC voltage diminish to nothing before securing it completely for maintenance.
NFPA 110 doesn't require an EPO, although an EPO does satisfy it. NFPA 110-2005 para 5.6.5.6 only requires a remote manual stop station be provided- this is often met simply by the generator control panel. I'm aware of no other regulations requiring EPO in Europe or the US.
The output filters on one UPS can have unwanted interactions with the input filters on the other. It can increase harmonics and circulating current and reduce component life. I say "can" because, as I understand it, it's very fuzzy, difficult to predict, and doesn't seem to cause any really...
This sounds like something the manufacturer(s) need to address. If these components are reliable enough that maintenance is not required or even recommended, than burying components is acceptable. But if it's just poor design... shame on them!
If you think that sounds risky, consider UPS...
Enkwizative, is this an electronic facility? Signals generated on the equipment ground at electronic facilities are typically at high frequencies and experience high inductive loss on a typical NEC-type single-point ground system. In these cases, an equipotential ground grid parallel with the...
Your best bet is to put a TVSS as close to the service entrance (and grounding electrode) as possible. If you're concerned about transients originating within the facility, place another TVSS on the panel that it's fed from.
If you're talking about a UPS on a US military installation in Europe, there is no hard and fast requirement on what training is required, and certainly no licensing. All the documentation is vague and subjective, but boils down to a judgment call on whether the personnel are trained and...
