The MCE105D can be used to get synchronizing and frequency/load sharing control of single or several parallel generators. It can also be used to export kW to mains or for Peak Shaving applications.
The MCE105D Generator controller provides potential free relay output commands to regulate the fuel supply to a diesel engine to control the frequency, synchronization or load sharing of a generator.
It forms the basis of the Megacon MXG105 Generator Control System and operates in conjunction with the new KSQ104x / KCQ104x (or old KSQ105) automatic synchronizer.
It should be noted that the MXG105 system will only provide load sharing control on generators with speed droop facilities, but it can do load sharing to a fixed shaft generator or to mains supply.
Functional Description
Frequency Control
The frequency of the generator is compared to an internal frequency reference. Each MCE105D has its own frequency reference so there is no need to select a master generator. All online generators act in unison, ensuring the quickest possible response to frequency variation.
Synchronization
In synchronising mode the unit receives a frequency deviation signal (mA) from KSQ104x / KCQ104x (or old KSQ105).
The controller responds to this signal by giving raise/lower commands to incoming machine’s speed control unit. The KSQ104x or KCQ104x will give the closing pulse to breaker when generator is within set limits.
Load Sharing
When a generator is synchronised to the bus, a generator circuit breaker auxiliary switch applies a DC voltage to close the internal load balance relay in the MCE105D. The load sharing line output signal must also be connected (in parallel) to other MCE105D online units.
In load sharing mode the unit receive a kW analogue signal proportional to the generator load from a power transducer (Megacon type MCxWx, MAG10x, KPW17x or similar kW transducer).
To allow for machines of different ratings, the kW signal recalibrated within the MCE105D to give the load balance signals an equal scale factor. This calibration is normally factory set but provision is made for fine adjustment of the load sharing during commissioning.
Changes in system load will cause the MCE105D controller to adjust the fuel supply to engine, each engine adjusting by its percentage share of the increased or decreased load. Concurrently, compensation is made for minor variation in system frequency, ensuring fast, smooth and reliable operation.
Note that in a MXG105 system there is no master generator setting, therefore
hunting due to the delayed effect of
cascaded controls will not occur.
In kW mode a 5kohm potmeter is connected to give a fixed generator power into the mains system. This generator power export is maintained regardless of variations of mains frequency. In this application the generator is both loaded and unloaded gradually by adjustment of the rate of change is made by altering the pulse rate and with control potmeters.
Interface to Diesel
The MCE105D is provided with Raise/Lower potential free relay outputs to operate directly to a motorised governor. Some newer electronic regulators also have digital inputs for speed regulation.
Should the speed regulator require an analogue signal then an electronic potentiometer of type MXR845CI2 or MXR845DI2 can be used as interface.
This DIN rail mounted potentiometer has a DC voltage or DC mA output with adjustable span, offset and ramp rate to enable it to be set up to interface to most electronic speed control units.
Load Output Signals
There are two analogue output signals available from each MCE105D controller. These are referred to as Generator Output Power and Generator Surplus Power.
These signals are normally calibrated to the same scale factor and can therefore be summated to give analogue output signal proportional to Total Generator Power and Surplus System Power.
The resultant signals may be used as inputs to indicators or to an analogue level instrument for load dependent start/stop, or load blocking function.
Mode Control
The various modes of control are selected by applying 24VDC to one of the mode control inputs (term. 16, 17, 18, or 20). Details of the switching sequences are described on page 3 (see datasheet).
