Progressive EMS-HW50C unit

For reference the Hartland Contactor in the EMS needs 88 votls to close and will drop out 20-77 volts, according to their website.

So yes, even in by-pass you will still get the contactor to open with extreme low voltages.

http://www.hartland-controls.com/#!blank/c1pqo

SoundGuy wrote:
Like you I much prefer the shorter delay of just 15" and would only have use for the longer delay during the summer when we might use the A/C. You're right - waiting for that delay sometimes seems like watching grass grow...

brulaz wrote:
Sheesh, you guys are so impatient.

I've usually got about a million things to do setting up camp outside after plugging in the shore power. So power's always on when those are done, no problem, and I've got the long time delay.

Yeah probably, but the reason we much prefer a travel trailer over any other type of rig we've ever owned before is so we have as LITTLE as possible to do to set up. :p In my case that usually means my wife is inside the camper as soon as the trailer is parked ... following that the first thing I usually do if she hasn't already beat me to it is run out the main service cable to the power post 'cause once the trailer has power she can do whatever she wants in there. Personally, I consider the trailer "set up" at that point as anything else is fluff that I can do later as I get to it, usually with a glass of wine in hand. :B

That said though it's not so much when camping that I find the delay annoying but when I may be working on the trailer here at the house and I have reason to disconnect & reconnect power several times. To date, if I plan to do it several times, I'll even unplug my hardwire EMS completely, which I can easily do because I wired it in with 30 amp connectors, but installing a switch that would allow me to change the delay from 136" to just 15" without having to open up the EMS and pull the delay jumper would for me be a great solution.

Learjet wrote:
For reference the Hartland Contactor in the EMS needs 88 votls to close and will drop out 20-77 volts, according to their website.

So yes, even in by-pass you will still get the contactor to open with extreme low voltages.

http://www.hartland-controls.com/#!blank/c1pqo

just the info I was looking for, thanks. So that indicated what I expected, the little honda 2000, doesn't just drop below 104V, it must be dropping down below 70ish volts, which is consistent with sound guys data. However, It only drops down for a fraction of a second, as soon as the relay opens, it pops back up, and relay closes again, then repeat.

Line power will very very seldom exhibit that type of behaviour, the line power is "stiffer", much lower source impedance so if it is dropping down below 70V you are REALLY drawing lots of power, Even a 75A load or so on a 15A branch circuit (what a 1hp motor draws for a few cycles on startup under load) will only drop the voltage down to around 100V, maybe 90 worst case.

However, I suspect the EMS electronics is designed such that it doesn't catch the generator short cycle dropouts AND it can't do anything about the relay chatter with generators, that's a mechancal/electrical function of the relay itself.

Learjet wrote:
For reference the Hartland Contactor in the EMS needs 88 votls to close and will drop out 20-77 volts, according to their website.

So yes, even in by-pass you will still get the contactor to open with extreme low voltages.

http://www.hartland-controls.com/#!blank/c1pqo

ktmrfs wrote:
just the info I was looking for, thanks. So that indicated what I expected, the little honda 2000, doesn't just drop below 104V, it must be dropping down below 70ish volts, which is consistent with sound guys data. However, It only drops down for a fraction of a second, as soon as the relay opens, it pops back up, and relay closes again, then repeat.

Yeah, exactly what happens with my own EU2000i, voltage momentarily drops to just 58 volts :E - short duration but enough cycles that even my $20 DVM can catch it, as shown in my video. Without the EMS in the circuit voltage does recover quickly but with it in place the contactor chatters like crazy.

Line power will very very seldom exhibit that type of behaviour, the line power is "stiffer", much lower source impedance so if it is dropping down below 70V you are REALLY drawing lots of power, Even a 75A load or so on a 15A branch circuit (what a 1hp motor draws for a few cycles on startup under load) will only drop the voltage down to around 100V, maybe 90 worst case.

I've never heard of line power being referred to as "stiffer" but yeah, that's about what it is. One of my videos I linked to earlier shows a nominal 120 vac 15 amp source dropping briefly to ~ 105 vac as the A/C compressor ramps up to speed, then recovers quickly following that - nowhere near the severe drop when source power is being supplied by my EU2000i genset. When I repeated this test back in the summer with my current Dometic A/C and the EMS in the circuit there was no contactor chattering at all when running on a 120 vac 15 amp line power source, only when the source was my EU2000i.

However, I suspect the EMS electronics is designed such that it doesn't catch the generator short cycle dropouts AND it can't do anything about the relay chatter with generators, that's a mechancal/electrical function of the relay itself.

Which I'm sure is why Progressive's official position is that their EMS is to be used only with conventional land line power.

On another related topic I went ahead and installed a switch in my Progressive EMS-HW30C so I can switch the delay from 15" (which I would use most of the time) to 136" (which I would use when running the A/C in the summer) without having to open the box and remove the delay jumper. Works like a charm. :B

Progressive Industries EMS-HW30C Delay Switch Mod (4 pics)

One way to think of generators vs. home power is this.

Your home power is close to an "ideal voltage source" That is, the power coming into the house will deliver whatever current it needs to while keeping the voltage constant. Your power line is close to that, what causes voltage to drop is the resistance in the wire between your meter and the device sucking power.

Now, most generators can be thought of as a "current limited non ideal voltage source" It will deliver reasonably constant voltage till it gets to is maximum rated current, then the current remains constant and voltage drops to support that current draw. The output impedance of most smaller generator is reasonably high. that is part of the reason you see the voltage vary by a pretty noticeable amount between no load and full rated load. In the case of the honda 2000, around 20 volts between no load and full load. In our house that same 15A load will show maybe a 1 or 2 volt drop at your outlet, and no measureable drop at the meter.

soundguy: nice way to change the delay. Yes, there are times when the longer delay would be the way to go with the AC.