EBME Forums Forums Maintenance Technical Assistance Inverters for use in vehicles

Hello Colleagues

Has anyone had any experience or got any info about using small (up to say 200 v/a) inverters onboard an ambulance for powering mains driven medical devices?

Yes I know most of this type of kit has its own internal battery when there's no main supply etc, but if anyone has used these safely and successfully could yo let me know please?

Many thanks

These links are as good a place as any to start your research, Rob.

We have used several 300VA inverters for some time on the transport incubators.

We opted for the pure sine wave type as previous experience using modified sine wave units produced noise on ECG traces. In its final from, in order to simplify things for the user, we also have a box that switches automatically which means that they only have one mains lead to worry about.

I spoke with the engineers at GMAS (now NWAS) regarding the current we require and they were happy that we are staying within their limits.

Only problem we have encountered is the internal fuse blowing from time to time. This has virtually erradicated since staff were reminded to turn off the inverter when connecting and disconnecting the 12V supply.

Rob,
Quite a few ambulances have them built in these days. Have a word with your local ambulance people.
Robert

Hi Rob

Yes we've used these on our SCBU transport system it comprises of a 300w inverter that powers a 6 way IEC outlet block to power an ECG monitor, pulse ox and a few syringe drivers. This system seems to work ok and has never given us any problems, mainly I guess due to the 6 way block, as there is only the option to plug the few leads into it that we have supplied.

Inverter - Mascot 9985 300W , RS 363-5306

Hope this is of some use.
Matt.

Hello chaps, thanks for all your replies thus far.

I'm meeting with our ambulance service (GMAS) this week so the more info I've got the better. What they have told me though is that none of their current fleet have inverters fitted as standard.

Matt: your solution seems really sound. Did you have to take any special precautions about electrically earthing the inverter case? I guess you fixed it onto some sort of trolley as it's a SCBU transport system?

Cheers

Hello all,
We were hoping to equip some ambulances here with inverters but we were told they would run down the batteries and could also be a fire hazard which seems like nonsense as long as they are fitted correctly and rated for the job.

Our main reason for having the inversters was for a fluid warmer as there no battery fluid warmers which can maintain the required temp.

Hi Rob,

Been and had a look at our system, I told you wrong this morning the inverter is a 150W unit, (Mascot 9984, RS 363-5299) this unit is connected to the 12v supply sockets within the ambulance directly (we needed to extend the supplied cable), the inverter number I told you this morning connects via “screw hook” terminals this unit wasn’t used in the end as these terminals in the ambulance we use to connect directly to the incubator itself.

Regarding the system itself we have a Drager TI500 bolted to a Ferno ITU six trolley, there are a number of bonding straps between the two units, (incubator and trolley) and the inverter and distribution block are fastened to a tray under the trolley, the inverter is bolted through some existing holes in the shelf and the block is simply sat behind it.


Hope that all makes sense!!
Regards
Matt.

Hi Matt

Thanks for describing your set-up and yes it makes sense!

Noticed that the inverter you've used is a modified sine wave version. Was there a particular reason you chose this over a pure sine wave version?

Also (I'm assuming it's a 12v type??), do you know the DC current consumption of the inverter when it's on full load?

Cheers

Rob

Modified sine wave inverters tend to be used as they are generally much cheaper than their pure sine wave counterparts. However, as we found out on our monitors, can cause noise to appear on the ECG trace even with the mains filter turned on.

Here we use a 300VA inverter to power an MP30, a PrinterNOx and up to 6 Asena CC syringe drivers. With everthing on and running we are peaking just below 10 Amps.