Powering an electric dive compressor

[Tornadosailing]

Originally Posted by Sawbonz

Impressive. I have bookmarked Coltri Sub MCH6 MarinePak Air Compressor from RCS and will definitely be in the market when the new ride arrives.

I recently installed a Nardi Atlantic 100 compressor on my boat. It has a 3hp 230V single phase motor, just like some of the Coltri models. I had a tight fit getting it into place, so the small size was a big factor.

Like you, I was worried about having enough power to run the compressor, and was looking at 3 phase and VFD etc. It doesn't seem to be necessary.

Here's the first test run on my 9KW Onan generator. The shore position on the shore/gen switch is to isolate the compressor from all other loads. It needs a new label though.

https://youtu.be/Y2-v8YVM0VY

[rcontrera]

9kW is usually no problem running one of the small compressors. It is the guy that insists on putting one of our babies on a 5kW or smaller gen set that we have to caution. When we get that small, the generator is doing all it can to power the compressor. Running anything else at the same time can drag down the generator a bit more and cause a little load slowing. That slowing decreases frequency and voltage which increases amperage. Now we start running into compressor controls overheating and burning out, high motor heat, high amperage through out the electrical system which can be damaging to anything that is running.

[BigBeakie]

Just finished testing a Baurer Poisidon PE100 (very similar to Junior) single phase 240v electric dive compressor by putting it on the oscilloscope at an electrical engineering shop, in order to measure the startup current and duration. What a surprise! No wonder folks are having trouble getting these to work well on inverters and some gensets😳

We made several measurements. Basically it takes 55 to 60 amps over a 900 millisecond period to start the compressor. This means we need about 12 to 13 Kw (60 A x 220V) out of an inverter to start it up, so even the Victron Multiplus 5000 that has 10Kw of maximum output capacity will not work.

And this is the ideal scenario since the compressor is brand new with no belt slippage yet. The 900ms could easily extend out to 1.5 seconds once some belt wear occurs.

But all is not lost as we are working on a solution that looks promising, so stay tuned.👍


Sent from my iPad using Cruisers Sailing Forum

[poiu]

Originally Posted by BigBeakie

Just finished testing a Baurer Poisidon PE100 (very similar to Junior) single phase 240v electric dive compressor by putting it on the oscilloscope at an electrical engineering shop, in order to measure the startup current and duration. What a surprise! No wonder folks are having trouble getting these to work well on inverters and some gensets😳

We made several measurements. Basically it takes 55 to 60 amps over a 900 millisecond period to start the compressor. This means we need about 12 to 13 Kw (60 A x 220V) out of an inverter to start it up, so even the Victron Multiplus 5000 that has 10Kw of maximum output capacity will not work.

And this is the ideal scenario since the compressor is brand new with no belt slippage yet. The 900ms could easily extend out to 1.5 seconds once some belt wear occurs.

But all is not lost as we are working on a solution that looks promising, so stay tuned.👍


Sent from my iPad using Cruisers Sailing Forum

There must be something else going on. You need to test with the actual equipment. I can start one with a Mastervolt 4.5Kw inverter.

[DotDun]

Originally Posted by BigBeakie

Just finished testing a Baurer Poisidon PE100 (very similar to Junior) single phase 240v electric dive compressor by putting it on the oscilloscope at an electrical engineering shop, in order to measure the startup current and duration. What a surprise! No wonder folks are having trouble getting these to work well on inverters and some gensets😳

We made several measurements. Basically it takes 55 to 60 amps over a 900 millisecond period to start the compressor. This means we need about 12 to 13 Kw (60 A x 220V) out of an inverter to start it up, so even the Victron Multiplus 5000 that has 10Kw of maximum output capacity will not work.

And this is the ideal scenario since the compressor is brand new with no belt slippage yet. The 900ms could easily extend out to 1.5 seconds once some belt wear occurs.

But all is not lost as we are working on a solution that looks promising, so stay tuned.👍


Sent from my iPad using Cruisers Sailing Forum

It takes that much because that is what's available. A motor will start on less current, it'll simply takes longer to spin up. You need to find the minimum it takes to start it and add a margin for wear/age.

[truckman]

[QUOTE=captmikem;2450376]I run a Bauer Utilis 10E with a 220/110 motor off my Westerbeke 7.5KW genset with no problems at all.

I used to run it off a Panda 4200 (which is more like 3KW) and as long as I would let the belt slip a little on start up it ran fine. A big cap (soft start) would have taken care of the start problem.

Capt. Mikem, Greetings from a fellow NWster. We are sailing on the US East coast now however. My question for you is regarding your experiences running a Bauer Compressor of your smaller genset. I'm looking to run a Bauer Jr. II 3hp single phase of my Northern Lights Kw genset. Do you recall the start up Amps you were seeing on your Bauer unit? I am having a lot of trouble getting anyone from Bauer or Northern Lights to say it should work as I have read accounts of many folks doing it. Also can you tell me anything about a big cap? or soft start and how that might help.

Thanks,

Dave

[truckman]

Originally Posted by nwdiver

Your 9kw northern lights will easily operate a 3-4cfm compressor, with soft start my 5kw northern lights works as long as no other loads are on the gen set.....

Could you give me the specs on your Air Compressor. I am trying to figure this problem out. I have a 6Kw Northern Lights genset and wish to run a Bauer Jr. II 3 HP model. Without modifications, but if I need a soft start kit or VFD I could do that just having trouble finding anyone with answers.

Dave

[njoynthewater]

I think you need to decide what compressor you plan on using. The higher the cfm the more horsepower you will need to power it. The small portable compressors typically have a relatively small motor driving them. You can purchase the portable compressor with either gas or electric motor. I suspect that the motor supplied is big enough to start the compressor under load so you might not need the maximum startup amps in the motor supplied by the manufacturer if you start the compressor with no pressure in the filter towers.

[captmikem]

Originally Posted by truckman

Capt. Mikem, Greetings from a fellow NWster. We are sailing on the US East coast now however. My question for you is regarding your experiences running a Bauer Compressor of your smaller genset. I'm looking to run a Bauer Jr. II 3hp single phase of my Northern Lights Kw genset. Do you recall the start up Amps you were seeing on your Bauer unit? I am having a lot of trouble getting anyone from Bauer or Northern Lights to say it should work as I have read accounts of many folks doing it. Also can you tell me anything about a big cap? or soft start and how that might help.

Thanks,

Dave

Dave,

I love it in the PNW, my boat happens to be in FLL at the moment though..

I think any 200mfd +or - say...30 mfd will work as a start cap, as long as it is valued over 220.

I do not recall the start up amps, but it would not trip a 50 amp breaker, however if you are 3 phase it will be a lot less. Three phase is nice, I used to run a boat where all the pumps were 308 3 phase and it was far more efficient and a lot less problem. Trouble is getting 308 3ph AND 220 /110 single ph out of the same gen set.

Using a soft start or VFD is ... pricey.. If you are handy, there are several DIY controllers on youtube, can't vouch for them, but hey if it is on the internet it must be true!

Actually trying to get info from Bauer on the motor is a hopeless endeavor, they only care about HP and torque, so you are pretty much on your own to put whatever motor on your compressor you wish. Rather than trying to use the one it came with it might be easier, cheaper, and more fun to match one to your gen set.
Just a note, be aware you can not use a start cap on a single phase motor that is in actuality a split phase motor, but you can on just about any other single phase. (A start cap makes the motor think it is a two phase motor for a bit).
You should not need and can not use a start cap on a 3 phase motor, it would just become confused.

Hope this helps, not gospel just what I have learned trying to get things to run.

Good luck and fair winds.

M

[HopCar]

I don’t know if this applies to dive compressors but I used a Supco Hard Start Capacitor to start an air conditioner with a little 1000 watt Honda. The air conditioner needed more than 3000 watts to start.
https://www.amazon.com/Supco-SPP6-Ha...keywords=supco

They should put a compression release on the compressor. That would make the starting load a lot lower.

[Olddan1943]

Originally Posted by HopCar

I don’t know if this applies to dive compressors but I used a Supco Hard Start Capacitor to start an air conditioner with a little 1000 watt Honda. The air conditioner needed more than 3000 watts to start.
https://www.amazon.com/Supco-SPP6-Ha...keywords=supco

They should put a compression release on the compressor. That would make the starting load a lot lower.

Yes, in theory, there is nothing to prevent you from starting the compressor totally unloaded and then loading it up SLOWLY. In practice, I would thought someone would have tried it by now.
Start with the discharge open, dryer condensate blow-down open and maybe the cylinder relief valves propped open too. Watch the amp meter. You may have to install a amp meter near the compressor, to maintain 'order'. When approaching the max PSI, again the there will be a increase of required AMP on the compressor. Instead of 3000 psi, you may have to be content with maybe only 2800 or 2500psi.

Prior to shutting down, unload the compressor again, in an orderly fashion, to prevent an electrical surges and strain.
The key here is to load and unload the compressor in an orderly fashion, taking the any strain and surges off the generator and compressor.
The manufacture tries to make each installation and operation idiot-proof, "Push the button and run installation."
We have to develop a work-around.
Granted, there will be limits of success to this too.
You may have to permanently install an Amp meter near the compressor to monitor and maintain 'order'. As the compressor heats up, the required amperage will decrease "a little bit".
I dont see the installation ever becoming a 'run unattended' installation.
Someone needs to find a on-shore installation to determine if this work-around actually works. Bring your amp meter.
Try it and get back with us. We all might be VERY surprised.
IF it works, write down the "orderly fashion" and keep it close to the installation, we dont forget a critical step.

[a64pilot]

I’m betting a 6 KW will power it no problem, as long as it’s not running AC’s etc also.

My gas power Bauer has I think a 5 HP gas motor.
6KW is over 8 HP and I’d bet an NL can handle quite a large surge, being able to do things like that is how they got their reputation.

[Tornadosailing]

I would be shocked if the Bauer doesn't have an unloader for the compressor. It would be almost impossible to re-start the compressor without it.

[stgermain45]

Can someone here recommend a make and model of single phase soft starter for my application? Yesterday, I purchased a Bauer Junior II dive compressor (JRII-E1-2HP). I went with the 115V version with 2HP motor as my plan is to wire it through my 2.5KW inverter (Mastervolt Mass Combi 12/2500-100) to power share with the 8KW onboard generator (Fischer Panda mini-8) when the load is ramped up. The boat is 100% wired for 115V and I'm choosing the simpler route of keeping the dive compressor 115V as well, despite marginally slower tank fills compared with the 3HP+ 3-phase compressors. I won't be running other large draw items like the water maker or air conditioning units when filling a scuba tank. In the compressor shop, we tested the startup on the Bauer and the inrush current was right around 100A. The draw was in the low teens after the initial inrush which will ramp up a bit as the tank fills.



Back to the soft start. I've seen the EasyStart recommended on this forum quite a bit for air conditioning units. I contacted Micro-Air yesterday and they did not recommend any of their soft starters for a dive compressor. Maybe a CYA thing, I don't know - but I don't see much in the way of published specs on their website.



Since this is a single phase application, I'm looking for a soft starter and not a VFD. Any tips would be appreciated!


Thanks,

Chris

[transmitterdan]

Chris,

Basically you need a single phase VFD. Program it to increase motor speed over about a 5-10 second interval. It will greatly reduce the inrush. I don’t think a soft start device will do what you want. Soft start devices work on air conditioners because at startup the soft start capacitor resonates with the motor coil to create the high current. But a 2HP single phase induction motor can’t be easily tricked like that.