Answers on a postcard . . .

[Steve]

What is this controlling then?

Untitled

• Steve
• 13 Sep 2014
• 1

Untitled

• Steve
• 13 Sep 2014
• 1

Untitled

• Steve
• 13 Sep 2014
• 1

Untitled

• Steve
• 13 Sep 2014
• 1

What are the two big square modules at the top with rotating levers on them?

This unit was generating an alarm at the time of this photo, I'm guessing because one of those modules had tripped, and again guessing that they are variable circuit breakers . . . What are the two slim modules adjacent to them?

The two modules below are contactors, but one of them has an attachment on top of it, I would guess this is a time delay unit to prevent both drawing their significant startup current at once . . .

I've said too much! Have a guess!

 

[JohnD]

I have a feeling they are for refrigeration equipment in a food shop.

 

[AndrewDavie]

Last pic looks like the countdown on a hollywood bomb.
But where's the red and green wires?! You need to have a 50/50 chance of disarming it!

 

[Steve]

I have a feeling they are for refrigeration equipment in a food shop.

Correct.

I didn't get a photo of the bottom half of this unit, which contains two compressors and (I think) a reciever similar to a workshop compressor. The unit provides refrigerant to 6 open front units in a convenience store. It is highly insulated to prevent noise going to the nearby flats and the compressors sit on shock absorbers, as does the whole unit. The fridge units have variable valves which continuously vary the amount of gas they let through to keep the temperature fairly constant. For this reason the reciever is essential or else the compressors may be running against any load - old fridge units have an open or shut valve which could just run from a compressor.

There is no electronic link between the fridge units and this pack. The controller in the pack I believe monitors the pressure in the reciever and fires up the compressors when it gets too low. The pack is capable of running on one compressor and I understand the controller will use them equally, only firing up two when one cannot keep up with demand.

Alas despite all the electronics, we did have a spectacular failure earlier in the year. The compressors have a heater around the base to prevent ceasing up during cold weather. One of the heaters had shorted to the compressor case. This tripped the C10 next to the controller and the C40 in the main DB. Unfortunately the C10 in the pack also powers the electronics! Not a great design. Lost all stock due to poor response time from engineers.

 

[bernardgreen]

The modules are motor protection devices

http://literature.rockwellautomation.com/idc/groups/literature/documents/ca/a117-ca903_-en-p.pdf

The module on top of the contactor is most likely to be an auxiliary contact block. Adds more switches to the contactor.

Best advice is leave well alone. If you do not have the knowledge to identify these items then you probably do not have the necessary knowledge to work safely on this equipment.

Motors that move when they should be stationary can injure people or cause serious mechanical damage. Tampering with the control system may result in a motor moving when it shouldn't.

 

[ericmark]

I have built similar looking units to power a concrete press but the Danflos unit is a give away something temperature controlled but would have expected to see around +4 or -18 for fridge or freezer.

The blue box looks like an inverter and below it some sort of pressure sensor although pressure can equal temperature.

From what you say I would expect the motors can run at variable speeds to keep the receiver topped up.

In the main units like this would have telemetry to tell a central monitoring station if all was OK and any failure should auto call engineer or at least the shop manager.

Clearly with a general power cut no point calling out a refrigeration engineer he can't do anything if no power. I know my son-in-law has been called out many times where he had to transfer stock because of a failure then transfer back once repaired they don't rely on the guy repairing in time.

Rummer has it Kuik Save got started by by insurance claims for failed freezers how much was true is another thing but I think insurers got wise and monitoring stations are now the norm.

When working on freezers back in 1980's it really annoyed me. One guy covered 510 km and if we had a failure he would be called but we would have to find what had gone wrong and correct it. We had no gas so often we would need to release gas to repair then evacuate and wait for freezer man who would just sit there allowing the gas slowly into the unit just watching the gauges. He had such a cushy number.

Of course now not allowed to release gas but then it was all freon 12.

 

[Adam_151]

There is no electronic link between the fridge units and this pack. The controller in the pack I believe monitors the pressure in the reciever and fires up the compressors when it gets too low. The pack is capable of running on one compressor and I understand the controller will use them equally, only firing up two when one cannot keep up with demand.

Is there not one of these in the system? http://www.adayiklimlendirme.com/uploads/images/markalar/rdm1.jpg

Of course the pack unit controller is capable of functioning without the RDM telling it what do do, but with an RDM combined with the correct mercury controller to the pack, the RDM can take charge and manage everything

 

[333rocky333]

I'm guessing because one of those modules had tripped, and again guessing that they are variable circuit breakers . . . What are the two slim modules adjacent to them?

Auxilary contacts, hence the "normally open and "normally closed" marked on them used to moniter if the switch is on or off, maybe just for an indicater light, or something more sophisticated like changing to the other compressor or whatever

Even some normal Mcbs have the facility to fit them onto the side by taking out a blanking plug

 

[Steve]

There is no electronic link between the fridge units and this pack. The controller in the pack I believe monitors the pressure in the reciever and fires up the compressors when it gets too low. The pack is capable of running on one compressor and I understand the controller will use them equally, only firing up two when one cannot keep up with demand.

Is there not one of these in the system? http://www.adayiklimlendirme.com/uploads/images/markalar/rdm1.jpg

Indeed there is Adam. But as said before, the RDM panel links to the fridge units and the pack, but it only monitors everything. It can also be used to set up the controllers on all the above too. Very clever stuff. However again, there is no direct link from the fridge controllers to the pack - they run independantly. The fridge controllers simply open/close their variable valves.

OOI, the RDM also monitors/controls the energy management system, and it is also linked via the EPOS system to head office who can dial in and change settings (and bizarrely have locked everyone else out of the RDM including the fridge engineers)

As said previously when the photos were taken the pack unit was generating an alarm on the RDM panel - I presume this alarm could be traced back to the tripped breaker pictured thanks to the aux contact, which would tell the controller a compressor had gone offline.

The compressors are not variable - they clunk on and off. Hence the need for a reciever in the system. Running a big compressor against one fridge valve open 25% would be a bad idea - it would just cut out.

Unfortunately if a fridge alarm is activated during the night, the RDM still relies on the intruder alarm link (From days gone by) to wake me up at 2am. This link is a simple on/off link in that the monitoring station cannot tell me whether it is serious or not - it could be a missed defrost (which fixes itself straight away) or the pack could have gone down (which needs urgent attention!). If the actual intruder alarm is activated we have a keyholding company - thanks for small mercies etc!