DALI Lights behaving strangely

This is the first site at which our company has used DALI system for tridonic ballasts. We had problems initially when scaning the for the ballast addresses we were not able to scan all the ballasts on the DALI network so we connected the tridonic power supply directly to the ballast in the ceiling and hence we were able to scan the entire network and address all the ballasts. Then we grouped the lights using the tridonic software and assigned the group to a cbus group using DALI and used this group to dim the lights from neo switches. All the rooms using dali were working fine for two months but then one of the room's lights started behaving strangely....if u turn the lights on or if u dim them to a certain level within a few minutes each ballast start going off one by one. We tried re-scaning, re-addressing, re-grouping changing the power supply but nothing helps so for now we hav disconnected the tridonic power supply and onl allowed on/off from the relay without dimming.
Can somebody please help me out here?

 

Status Correction

Hi,

This sounds to me like the Status Correction function in the C-Bus DALI Gateway may be going wrong. Can you try disabling Status Correction from within the toolkit UI?

If it is status correction, the most likely cause is control of DALI fittings from anywhere else other than the gateway. Are you using any DALI input units, or a second gateway?

Cheers,
Mark.

 

We are having exactly the same problem on our site as Dragshot.
There is 1 PS in this DALI network, the ballasts are Tridonic Atco PCA Excel one4all of various wattages. Like Dragshot, all the lights behaved perfectly for the first month or so and then some (but not all) suddenly started switching off after a some time (from a minute to several minutes from turn on).
On the DALI gateway we are using "Match Ramp Rates from C-Bus to DALI" and but "Status Correction" is switched off.
We too have gone thru changing addresses (both DALi and C-Bus), changing ballasts, cable.
When required, the lighting is grouped in DALI (using Tridonic's Configtools) and so a single C-Bus address is used to control this group.
There are no DALI input devices and only one gateway is used.
It is also clear that the controlling C-Bus address is still ramped up when the light turns off so not a C-bus command that is turning the light off. C-Bus diagnostics shows no traffic or errors when the light turns off.

 

DALI bahaving badly

I have done numerous DALI installation and usually find this beahavior is normally found when the DALI Gateway is first powered up.

Is it possible you are losing power to your network???

 

I am working with Dragshot on the same project and we would like to provide additional details regarding the hardware and software we have used.

The room in question has 57 light fittings and each of these are fitted with Tridonic Ballasts. The information printed on the ballast is as follows - Tridonic PCA2/26 TCD Excel One4all with TC DEL 26W & TC TEL 26W. The Lamps being used are OSRAM DULUX 26 Watt lamps.

All these lights are connected to each other with 1 sq mm cable which is then connected to a Tridonic DALI PS1 Power Supply which outputs 200mA. Finally the cable is connected to the C Bus DALI gateway.

We used Tridonic ConfigTOOL V1.5 DALI software to scan and group the ballasts. After which the group were then mapped to a C Bus group address in the DALI gateway.The whole system worked fine for about two months then lately we were informed that the lights turn off one by one once you switch them on. We have used only one DALI Power supply unit to power the network and found that once we disconnect this from the network, the lights stop turning off by themselves. We first disconnected the C Bus dali gateway but it did not make a difference. Then we tried replacing the dali power supply but found the same behaviour.

Since the client wanted to use the room, temporarily we have disconnected the DALI PS so now the lights don't turn off themselves and since the main power circuit is connected to a C bus relay module we have programmed the neo switch to just turn on/off the lights.

We have two rooms connected to a single dali gateway unit. One on the A terminal and the other on the B terminal. The dali lights in the other room are working fine. The rooms are identical and it's strange that we have a problem only in one of them since both of them use a single dali power supply.

Do you think adding another power supply is advisable ??

 

DALI bahaving badly

Hi Ashwix,

you mention the problematic room has 57 lights installed, and also mention you have two rooms, one of which works fine.

Are the light fittings in the other room part of your count of 57 fittings, or are there more????

If you have additional above the 57 mentioned, perhaps there is a voltage drop problem on the DALI loop cabling.
You mentioned you have tried changing the DALI PS, so am i correct in assuming you have a spare DALI PS??

I would install it on one of your DALI loops and see how it goes.

All the best!!

 

Do not connect two dali ps's to a network!!!

Hi Guys,

No! One DALI PS per network is the absolute limit!

DALI is very different to C-Bus. Comms work by the transmitting device shorting the bus to create a pulse of low voltage, then releasing the bus to let the voltage rise again. This works as the power supplies are current limited to 200mA (or maybe 250mA, cant remember) and all transmitting units are capable of sinking this current (and a small safety margin more) when they transmit. If you add a second DALI PS, your network will be current limited to 400mA, which the transmitting units are not guaranteed to sink. The best possibility is comms don't work, the worst is you damage the transmitting circuitry in all your ballasts and the DALI Gateway.

Cheers,
Mark.

 

DALI Fun

Hi Again,

Hopefully you haven't cooked your units, so let have a look at the rest of your post

With no PS, there are no DALI comms, so ballasts will go to their fallback/safety level, which is usually ON.

Was the DALI PS connected at this time? If you have a DALI PS on the network, but not the C-Bus Gateway and the loads are still turning off, then its something on the DALI side.

Yep

My personal suspicion is it is something to do with the Status Correction feature in the DALI Gateway. Did you try turning this off and see what happens?

If you turn off Status Correction and the problem still occurs i would try to get some logging data. Depending on which DALI pci thing you have, you should be able to log commands on the DALI network. You can also get a application log of C-Bus out of Toolkit. Try watching these when the lights turn off and see if any commands are being sent on either network. If so, we should be able to chase it down. If not, its probably something electrical.

Good luck!
Mark.

 

DALI bahaving badly

Sorry if my response was not accurate.

I assumed reading the prior posts only one DALI PS was being used for both DALI universes -or gateway outputs.

My mistake!!

 

Additional Comments

Hi Everyone !!

I would like to comment on some of the stuff we have been discussing so far. Firstly just so everyone knows, both the rooms have their individual DALI power supply units which power each of these rooms seperately. The only contact point for both the identical room network cables is the C Bus Dali Gateway. One room is connected to terminal A, while the other room is connected to terminal B. So both the rooms are not interconneted as they are on seperate networks.

Other comments :

1) From what i know, a single DALI network cannot have more that 250mA of power. Now since the Tridonic PS supplies 200mA we should be using only one and adding more is not going to help.

2) When we send a broadcast command to turn on or off all the lights, all the ballasts respond. So it seems like the communication is ok. However it could be that the voltage on the network could be dropping of at some point.This maybe either due to the cable length or for some other reason. I'm not quite sure about this, as occasionally we are not able to scan all the devices.

3) If the power is dropping of at some point maybe adding a power supply might help to boost the signal if there an absolute dead zone but since the DALI network uses a max of 250mA i'm not to sure adding a power supply is recommended as it could cause a burn out.

4) Even with the Dali Gateway diconnected and the DALI PS connected the lights turn off by themselves. This means that even though the C Bus Dali is not communicating any information to the network, the ballasts themselves are switching off due to a possible factory setting. I spoke to a guy at Tridonic and he said he will try to find out if that could be something we should be looking at. Meantime if anyone on the forum can speak to their respective tridonic representatives we might be able to get more info.

Lastly a reply to Ashleigh's post.

Yes we have only one PS per Dali network and there are no other control devices other than the C bus dali gateway. Nothing was changed at site from the day we commissioned the system upto the day the problem occured.

We changed a few ballasts but even the new ones respond in the same manner. So it looks like the lights are doing their own thing.

I should be able to get the firmware version of the Dali Gateway and the setting by tomorrow though.

 

Was there a solution found for this? We are experiencing exactly the same problem with a 6-fixture DALI network (2 DALI groups with 3 fixtures each - being controlled by 2 C-Bus group addresses). When the DALI fixtures are turned on, individual fixtures will randomly dim to minimum level after a few minutes. Over time we've seen all 6 fixtures do this independent of each other.

Also - We're controlling the on/off with a Clipsal relay, and when the DALI fixtures are in a dimmed state (say 60% for example) and are turned off and back on via the relay, some of the ballasts come back at only minimum brightness. The DALI level must be cycled with the Clipsal button (memory dimmer) to get the DALI to return to the desired (preset) level.

Appreciate any update you folks have on a solution to either issue.

-Duke

 

DALI current and voltage

Here are a few helpful ideas.

Check your current draw from the DALI PS. Make sure that it is not exceeding the 200ma it is supposed to produce. Check your DC voltage at the source and at the last ballast (or farthest from the supply) to make sure your voltages are in tolerance. There is a DALI handbook I've attempted to attached which details the acceptable ranges for both.

Assuming your current or voltage is out of limits, it is possible that a bad termination or bad connection is creating a problem on your network. Try splitting your DALI network in half temporarily (you will need two DALI PS for this) and see if the problem affects both halves. Continue splitting until you identify the specific ballast or termination that is causing the problem.

Hope this helps everyone.

 

DALI includes settings relevant to DALI power being connected / reconnected...

BTW - Dropping power to the DALI network when all ballasts are turned off is not the good idea some think it is. This type of arrangement is against the DALI standard and some ballast manufacturers will void warranty if they discover that is how they are being used.

Sounds like you need to look at how your ballasts are programmed. When the DALI network power supply is lost then returned the ballasts will recover to a programmed level - default = 100% (sound like yours might be set to a low level ???) so when power is applied they will go to that level. This also allows basic test / control, without DALI comms. Check your DALI network is not falling over and don't ever switch the DALI network PS like some others recommend.

 

when the DALI BUS go failure, lamps on the BUS will be turn on to the max level. our ballasts work this way.