Mitsubish Mr Slim PL42AK power spike

[Ront]

Hi all,

We have two PL42AK indoor units with the corresponding PU42EK7 outdoor units currently in our server room (The PU42EK7 are mounted outside). The units work almost flawlessly, except when there is a power spike (brownout, whatever...). If we have an outage in the units (power out for a minute or so) the units start back up without an issue, from this I can assume that from the manual the "indoor controller board" SW1-8 is set to on, so there are no problems there. Our problems happen when the blip in power is momentary, or that the outdoor unit does not get power for a couple of minutes (I believe this causes the temperature to rise in the piping and then the indoor unit issues an error code). This causes the indoor units to shut down and flash P8 unit they are reset by the controller. I would like the indoor units to run all of the time and not shut down for any error code that may be detected from the outdoor unit (or in the temperature of the piping), would setting the dip switch SW1-7 the "Switch for detecting abnormalities in the outdoor unit abnormality detection" to on stop the indoor units from shutting down? and if the outdoor units regain power will it start cooling again? or are there other ramifications that I am not aware of that may damage the units?

I have looked through the forums and talked to our vendors, nobody seems to be able to help, of course I may be searching for the wrong terms.

Any help is appreciated we are about to enter the spring here and the thunderstorms start playing havoc.

Thanks,

RonT

[Brian_UK]

You could cause a major failure if you attempt to bypass or ignore fault codes on these systems.

As the units restart on power restore I would suggest that you install power monitoring contactors on the unit power supplies.

In the event of any power disruption or variance from normal the contactors will drop out and create a proper power failure to the units. This should overcome your transient power glitches by forcing them into power fail mode.

edit: Something like these....
http://stevenengineering.com/Tech_Support/PDFs/45RPHS.pdf

[Ront]

Thank you for the suggestion, I will contact our contractor to see if he can install these. Do you know of any way to remotely start these units? or control them from a web application? We have recently started to use APC AC in our collocation and they have Ethernet interfaces so we can remotely diagnose and restart them if needed.

Thanks again,

RonT

[Thermatech]

In Europe Mr Slim split system indoor units can be fitted with 3 / 5 wire adapters to provide simple remote run / stop / fault indication. This can then be connected to your BMS system. It will only indicate there is a fault but will not give fault code.
Its very cheap option & easy to connect to the indoor units.
But your units in Canada might be different so you would need to check with your Mitsubishi supplier.

If you want to spend lots of $ then fit A to Mnet adapters to the outdoor units & connect to a G50 or AG150 central controller.
The central controller has IP address so you can connect to BMS system with a Mitsubishi interface or on some BMS systems directly with network cable.
Then you can have full remote control of on/off , fan speed , mode , set temp via remote BMS.
The full fault code will be reported to the BMS & you can have auto text message to service engineers mobile phone with fault code when the system stops on any fault.
Again we do this alot in UK but then Mr Slim units for all Europe are made in UK. But the systems you have may be different.

Standard mass produced split systems tend not to have any type of power supply protection fitted to the system. So it is the endusers responsibilty to ensure correct power supply to the units. Electrical contractors can install standard power supply protection components which will auto shut down if there is any power surge / spike or if any phase is lost to any critical equipment.

[Ront]

Thank you all for all of you answers, but two things are still confusing me,

1. Your saying that the units come with no power protection built in, so that when the unit experiences a quick fault like a brownout or spike the outdoor unit will just shutdown till it receives the power on signal from the indoor unit? Seems a little silly to me that it would not have any fault protection built in, but then again I don't work with AC all of the time.

2. What would be the use of putting the dip switch SW1-7 the "Switch for detecting abnormalities in the outdoor unit abnormality detection" in the unit in the first place? testing? I'm just curios.


Thanks again for all of your help,

RonT

[nike123]

I really don't understand you IT peoples. Would you expect that your butcher cool meat with Comfort cooling air conditioner? Of course, you will not. But when it comes to your equipment, then it is normal to cool servers with equipment not designed for that purpose.
:eek::eek:

[Ront]

Thanks for your comments nike123, but that is not really what I asked. You are welcome to your opinion.


Thanks,

RonT

[Thermatech]

I am wondering if perhaps what you have is the very old K series Mr Slim systems which ran on refrigerant R22.

In this case there was no direct data communication between indoor unit & outdoor unit.
The indoor unit just sent 12v dc command to run compressor on/off.
The indoor unit was monitoring the refrigerant pipe temperature all the time & if compressor on command sent but no pipe temp change within a few mins then stop on P8 fault. This is displayed at the remote controller & just means there is some unknown fault with the outdoor unit which needs to be investigated.

This was very basic electronic control by modern standards & we moved on to A control Mr Slim systems over 10 years ago. Not so many of those old R22 systems left operating here in the uk as we long since moved on to R407c & now R410a equipment.

Generally no standard mass produced split systems are designed for use in computer rooms with very low humidity because computer rooms have high sensible heat load & little or no latent heat load. Mr Slim systems are only rated down to 15 deg C wet bulb indoor room return air temperature & need some latent heat load with humidity to work correctly.
So although lots get installed in computer room applications we try to encorage contractors & endusers to install proper high sensible cooling close control systems in computer rooms.
For example Mitsubishi Electric make dedicated City Multi PFD type high sensible cooling systems for computer room applications.