Electrical Management Systems questions

I understand now. I thought it must have something to do with the sine wave form of specific generators, and not something as simple as an unbonded ground/neutral.

I really like Bobbo's solution, and the idea of not bypassing the safety aspect of the EMS.

Planning......judging by your pictures you are successfully running an EMS with the modified male plug at the generator. Do you routinely do this or use the bypass feature of your EMS??

road-runner wrote:
There is no issue with using an inverter generator. The issue is with the generator having a floating output as opposed to a bonded neutral. Some non-inverter small generators also have a floating output. When the EMS senses a lack of continunity between the ground and neutral wires, it mis-diagnoses the situation as an open ground. The plug-in outlet testers make the same incorrect diagnosis.

One slight correction. It is diagnosing the situation exactly correct. Open ground. In a main service panel the ground and neutral are bonded together. Every panel after that is a sub-panel and the neutral and grounds are kept separate.

The generator is the Power Company and is the place that the neutral and grounds are bonded. Since the generator is not bonded, the ground is not connected. Think OPEN. Hence the OPEN GROUND indicator. Someday Gen manufacturers are gonna wake up.

There is no issue with using an inverter generator. The issue is with the generator having a floating output as opposed to a bonded neutral. Some non-inverter small generators also have a floating output. When the EMS senses a lack of continunity between the ground and neutral wires, it mis-diagnoses the situation as an open ground. The plug-in outlet testers make the same incorrect diagnosis.

dryfly wrote:
I understand, regardless of the issue, why bypassing the EMS would work, but that seems like a lot of work.

We have a hard-wired Progressive Industries EMS-HW50C. Integral with the system is a control/display panel with a switch that allows you to bypass the EMS for generators with unbonded neutrals.

PI actually used to sell a pre-made plug to plug into generators similar to the illustration above. (I have one, and use it on a small faux Yamaha inverter genset.)

The EMS will not allow unbonded neutral power into the coach as part of the protective schema. The plug simulates a bonded neutral on the generator.

Or, as I mentioned, I can bypass the EMS and allow the genset to power the coach, but that eliminates the protections of the EMS.

OK, but first help me understand why there is an issue with the use of an inverter generator and the EMS system. Is the EU2000 a modified sine wave inverter?

After that maybe I can understand why bonding ground and neutral is a solution. I just found the Progressive Industries remote bypass switch, and this may be the easiest solution.

Again, I really need to understand what the problem is before I attract a solution.

The PI external EMS systems that plug into the pedestal sure seem to be an attractive solution but if I had one it would get stolen the first week!

Or use a "patch board" approach so the EMS can be wired around.

Or just use the bypass switch.

Build a bonding plug. About $3 if you do it yourself from stuff bought at a big box hardware store.

1. Replacement 3 prong plug
2. 3 inches of wire

Open the plug and use the wire to connect the GROUND pin to the NEUTRAL pin. DO NOT CONNECT ANYTHING TO THE HOT PIN!

Close up the plug and plug it into an outlet ON THE GENERATOR.