Caterpillar synchronization

[alehman]

I have two Cat 3512BDITA 1.5MW DEGs with EMCP II and ADEM controls. We need to synchronize the outputs to a utility source (without actually paralleling) so that static switches supplied from the generator and the utility source can operate in fast transfer mode whenever possible.

Does anyone know if this controls package has synchronization capability?

Thanks,

Alan
“The engineer's first problem in any design situation is to discover what the problem really is.” Unk.

 

[catserveng]

There are two possible speed reference options in the combination you describe, a CAT "speed brick" or a Woodward LSM (Load Share Module).

The speed brick is normally provided for single unit operation with an EMCP mounted speed adjust potentiometer to allow the operator to adjust speed.

The LSM option is provided for units paralleling with the Woodward load share lines type network. The LSM has a sync input circuit compatible with Woodward (and similar type) synchronizers.

Hope that helps, Mike L.

 

[davidbeach]

Regardless of how good the controller is, you will find it moving in and out of synch repeatedly as loads on the utility change. It's one thing to ask an autosynchronizer to get you lined up for a 15 or 20 second window, another to want to hold it there for the long term. Then, as soon as your static switch drops load onto the generators you'll lose synch anyway.

 

[alehman]

Catserveng - I do have the speed POT (and voltage) on the controller. Is there a formal name for the "speed brick" I should mention to my dealer?

Dave - I assumed that any time there is a significant change in load, synchronization will probably be lost until the governor "catches up". This is a request from my client and I'm not sure how well it may work. My thought on response after transfer is that loss of sync wouldn't matter until it's time to transfer back. Any further input is appreciated.

Alan
“The engineer's first problem in any design situation is to discover what the problem really is.” Unk.

 

[catserveng]

The "speed brick" is a 9X9591 module, it is approximately 5"X4" and mounted on the back pan of the EMCP II enclosure. If you have a speed adjust potentiometer then you should already have either a speed brick or an LSM installed.

Depending on how you are going to try and maintain sync speed, the input to the speed brick is 0-5 VDC and I have used a PLC output to drive it in some systems. Note the speed range has to be set in the ADEM ECM to meet you actual needs. The ECM will detect a speed reference (throttle signal) fault if the PWM signal is below 5% and above 95%. If the throttle signal is out of range the ECM will drive the engine speed to the programmed idle setting.

Are the units going to be paralleled with each other while islanded from the utility? Tweaking the speed reference will affect the units load sharing if so. If this is the case then you may want to consider a system like a Woodward DSLC on each unit with frequency trim enabled.

Mike L.

Phoenix also makes a multifunction signal convertor that can provide a speed reference signal (500 Hz PWM) to a CAT control, don't have the part number handy but if you need it let me know and I'll dig it up. Axiomatic also makes signal convertors that will provide the correct speed reference signal.

 

[FreddyNurk]

Is the reason for using static switches to avoid paying for the much larger switchgear required to handle the combined fault levels for a grid synch package?

 

[alehman]

Mike - The generators will not be in parallel. Thanks very much for your help. It looks like I need to research what we have.

FreddyNurk - No. This is an existing system. The generators are isolated from each other and from the utility. The static switches are downstream of a UPS. Synchronization is being attempted the static switches can operate in fast-transfer mode.

Alan
“The engineer's first problem in any design situation is to discover what the problem really is.” Unk.

 

[ScottyUK]

Normally the UPS output inverter will sync to the bypass supply. If you feed the bypass from the generator - via an ATS if necessary - then the inverter will sync to it. The inverter is a heck of a lot faster to respond than a governor.

This system sounds like it may introduce more failure modes than it eliminates...?


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