RELDN12 (L5512RVF) Relay Logic

I have recently installed a 13 kva Generator on my rural property. The property is controlled by C Bus & Homegate.
Although there are eight RELDN12 relays only five are controlling 240 VAC. The others are controlling 24 VAC. On the 240 VAC relays are units such are numerous Pumps which draw significant current on start up. That is they kick back in when the generator tries to start and supplies the initial power supply.

The problem is that the Generator will not start if there is too much draw during it's start up phase. The only way I can get it to start is too physically turn off the main power feed to the C Bus relays.

Now, I have tried "Recovery" & "Restrike" but immediately the power comes back on it takes a few seconds for these modes to work hence the generator senses the draw and does not start. The relays do not have a Hard Start Tab but do have a Logic Tab.

Can someone advise me if using this Logic Tab will work and how it does work as the trials to date are playing havoc with my associated IT network hardware (have blown one switch so far)?

Regards,

Colin

 

Hi Colin,

You'll probably get plenty of ideas back here, this is just my initial thought.

If I am to understand your scenario, you are saying that when the power goes off and you want the generator to 'automatically' kick in, the C-Bus resets/powers up and the relays go back to their previous ON state on the pumps and the inrush current to all the pumps starting together then overloads the generator? Is that correct?

It seems that if the C-Bus network was kept active in the event of a power failure, the C-Bus relays and the HomeGate logic could first shut down the ON relay circuits and then execute a staged restart of the previously ON pump circuits when the generator is online.

Putting a UPS on the supply of the C-Bus relays logic side (and any other require/intermediate power supply / bridge / system units as well) and the HomeGate PC could keep the C-Bus network up. From there, if you banked together several pump circuits using the Logic Tab on the relays you could bring the pumps back in groups eg. All Front paddock irrigation, All West Paddock irrigation. You could have the logic sense a power outage either through the UPS trigger link (serial port command or switch output) or a 240v relay to a bus coupler and have some logic that collects the status of the relays at the time of the outage, turns off the pumps or pump groups and then restores them sequentially after the Generator is online.

You could also use the re-strike delay feature you've already been trying to do it effectively (if you wanted to reduce the complexity of the restart logic program) as the C-Bus network itself wouldn't be down due to the UPS.

Brad

 

If the relays are losing power, why can't you just set the power recovery to all off on all the channels?

 

Can you use the Stagger functionality on the recover tab to spread the restart load over a period of time?

 

B Merrick,
Yes I considered the UPS but discounted it due space and wiring issues on the main C Bus Board. I think I will go with your idea of the Bus Coupler as this will probably solve the problem. Prior to that solution I will investigate the Generator Automatic Transfer Switch to see if I can put in a Dry Contact Relay that will be open until the Generator has gone through it's warm up period and is fully up to speed before it takes over the load. Thanks for your help.

CCS

 

Ashley, The relays are not losing power. The problem is that they lose power naturally after the Grid fails but come back on immediately the Generator tries to start and supplies power. The relays then do not have enough time to set the "Restrike " settings and switch off running units before the generator immediately senses too much load

Regards,

CCS

 

Chromus,

I have tried both Recover and Restrike.

The problem is that the relays lose power immediately after the Grid fails but come back on immediately the Generator tries to start and supplies power. The relays then do not have enough time to set the "Restrike " (or "Recover") settings from "power on" to the settings I have made to switch off running units before the generator immediately senses too much load.

I had tried staggering the restrike up to 3 minutes across about 10 power supplies but as above, the restrike remembers the previous "power on" setting and then it takes just a second for the restrike to set the supply to off. By that time the Generator senses the load and shuts down.

I think Ashley above may be on the right track.

Thanks anyhow,

Regards,

CCS

 

Another option would be to take to power to the relays via a holding relay. This would disconnect the instant the power failed. Once the generator was stabilised and the cbus relay had finished it's startup, you could just pulse the holding relay to close it again then sequence the rest of the startup.

 

I was going to suggest a similar solution. Use a delay make relay. When power returns the relay will delay the relays from getting power, thus allowing for the generator to get up to speed and for the C_Bus units to power down and then power up and use the re-strike feature.

 

Hi
The relays in the 12 Ch relay unit are a magnetic latching type so if relay is closed and power goes off the relay stays closed and when power returns whatever is connected will be supplied power then a few seconds later the cbus control will set the relay to whatever you you have set in the recovery tab of the relay. To overcome this I have run a UPS for CBus Control and PC/Homegate then sense loss of mains via AUX Unit plus Phase failure device and some logic in homegate to set relays off you can then decide how you need the loads should come back on ie:- load sheding etc.

 

Hi all,

Yes the UPS is one way but I think Ashley's & Znelbok have come up with my preferred options. I will do some more research on the Automatic Transfer Switch to see if there may be a solution there and if not go with the Delay Relay or Holding Relay options.

Thanks muchly.

CCS