MEP803 120/208 Volts 3 Phase VS MEP804 240/416 Volts 3 Phase

[cowboy3500]

Hello,
I have the MEP803 generator to run a 10 HP three phase motor. I am trying to figure out whether that generator will run my 10 HP 20-230/460 Cardboard baler. The description on an MEP803 says 120/208 volts, so I'm assuming it won't work because of the low voltage rating but for the MEP804 it says 120/208, 240/416 Volts 3 Phase. I don't have a deep understanding of three phase but would the MEP804 run my 3 phase motor? The motor tag is attached.
Thanks,

 

[grywitt]

Hello,
I have the MEP803 generator to run a 10 HP three phase motor. I am trying to figure out whether that generator will run my 10 HP 20-230/460 Cardboard baler. The description on an MEP803 says 120/208 volts, so I'm assuming it won't work because of the low voltage rating but for the MEP804 it says 120/208, 240/416 Volts 3 Phase. I don't have a deep understanding of three phase but would the MEP804 run my 3 phase motor? The motor tag is attached.
Thanks,

Its possible it will run it. It is within its specs to do so but inrush current will be the deciding factor. Motors when starting pull a lot more current than after they are running. Depending on how much load it's trying to take on when it starts makes a lot of difference. When calculating watts when using three phase you need to multiply voltage times 1.732. So for that motor at 208 volts its 208 X 1.732 = 360 X 24 FLA = watts 8640. Most motors aren't running at there full load either so it will probably be running at lower watts than that even. ( my numbers above are rounded a bit). the only way to know for sure is to try and if it doesn't start it see if there is some load you could disconnect while is starting. We have a hydraulic pump here at work that requires way more power to start than running amps but it is trying to start not only the hydraulic pump but the hydraulic fan act so its working really hard at start up. I am pretty confident the 15K should start it on the 208 setting. Motors are tricky when it comes to starting them especially if its close. Hope this helps a little.

 

[grywitt]

Hello,
I have the MEP803 generator to run a 10 HP three phase motor. I am trying to figure out whether that generator will run my 10 HP 20-230/460 Cardboard baler. The description on an MEP803 says 120/208 volts, so I'm assuming it won't work because of the low voltage rating but for the MEP804 it says 120/208, 240/416 Volts 3 Phase. I don't have a deep understanding of three phase but would the MEP804 run my 3 phase motor? The motor tag is attached.
Thanks,

by the way the beginning of my last post was about the 10K gen then at the end was my opinion about the 15K. I reread it and realized that wasn't clear

 

[rickf]

Is that a capacitor start motor? If so the inrush will be a little lighter. I am guessing the baler is hydraulic so all the motor is running is a hydraulic pump. With all the controls in neutral at startup I would not think there would be a huge current draw to start.

 

[kloppk]

The MEP-803A can be set to output one of three different Phase/Voltage settings.
1) 120 volt
2) 120/240 volt Single Phase
3) 120/208 3 Phase

The output specs for the MEP-803A.
The first voltage is the phase to neutral voltage. The second voltage, if listed, is the phase to phase voltage(s)




The MEP-804 can only output 3 phase power.
The MEP-804A can be set to output one of two different Phase/Voltage settings.
The first voltage is the phase to neutral voltage. The second voltage are the phase to phase voltages

 

[fb40dash5]

With all the controls in neutral at startup I would not think there would be a huge current draw to start.

I'm not a millwright, but wouldn't the motor usually be on demand? I.E. hit the compress button, the motor starts, and the "extend" valve is engaged?

 

[grywitt]

I'm not a millwright, but wouldn't the motor usually be on demand? I.E. hit the compress button, the motor starts, and the "extend" valve is engaged?

Yes mostly. Like Rickf said above it probably doesn't have much load to start but not knowing the machine it's possible for it to draw quite a bit during start up. I agree that it probably will run it especially since these 803A's are really more of a 12k gen.

 

[fb40dash5]

I mean, my point was, wouldn't the motor not be running deadhead? I wouldn't think the motor would sit there running, spinning the hydro pump, and then only be loaded when you want to use it.

I'd assume it sits there motionless, and when you hit the "smash" button, it starts the motor & sets the valving to "smash", so the motor is (basically) starting under load. (Depending on motor startup time, and if it's literally instantaneous, how long the valving takes to respond, since we're talking milliseconds)

 

[rickf]

The start on demand is usually a DC thing. Plow motors, tailgates and that type of thing. For industrial power equipment the pump will be running all the time. The pump will not deadhead due to open center valves. Think about a log splitter or a tractor and loader. Pump is always running as long as the engine is but no motion from the hydraulics until you move a valve to redirect fluid to the cylinder instead of just circulating back to tank.

 

[Guyfang]

Here in Germany, I believe we would use a Star Delta switch to reduce start up draw? Or am I dreaming?

 

[grywitt]

Here in Germany, I believe we would use a Star Delta switch to reduce start up draw? Or am I dreaming?

The first time I saw that setup I was stumped for a while looking at it thinking if the contactor drew in it would be a direct short phase to phase. Then I got my hands on the schematic and realized what was going on.

 

[2Pbfeet]

Usually those balers have a contractor (switch) to interlock the access. That means that the pump only comes on when the cycle switch is activated. (Uses less power).

@cowboy3500 You might look in your owner's manual for the control circuit. This manual is for a similar sized unit;

https://www.aceequipmentcompany.com/assets/docs/Vertical-Baler-6030HD-Manual.pdf

I think that @Guyfang's idea of adding a star-delta starting switch or perhaps adding a VFD would reduce the wear and tear on your generator, regardless of whether it is an 803 or 804. I do think that the 803 would have a hard time starting it, as the 208 rating on that 10HP is very close to the upper limit for an 803, as @kloppk pointed out. Three phase motor inrush currents may only last 4-10 cycles (75-150msec), but that is a long time for an inrush current that can be 5-12 times the running current. I.e. hard on a generator.

All the best,

2Pbfeet

 

[Guyfang]

Star Delta is in extremely wide use here. I never saw one in the Army, and was blown away at the Trade school at its simplicity. I too thought it would be a direct short. Works great.

 

[G744]

Don't forget to turn up the regulator voltage until you get 277/480. 240/416 is an archaic spec, mainly set up for 240 Delta needs.

Motors don't like undervoltage conditions, as they consume kW irrespective of E/I availability. In other words, if the E is low, the I will be higher and can lead to burning out windings. They will tolerate nominal overvoltage without harm.

Our submersible well pump is a 480 3ph unit, and in Winter the grid line is close to 500V. It's just fine with that.

I've rebuilt many large gensets for clients over the years, and most of them were dataplated as 240/416 sets. With all new metering, they have the 'green range' voltmeter starting at 460 to 490V.

BTW, 3ph motors in your HP range don't have any circuitry for starting, other than a line contactor with overload trips. They just go to work without those big amp surges found with single phase motors.

 

[grywitt]

It's amazing how much knowledge is on this site..