The Be124 generator control unit is a multi-processor digital controller. The main function is the control and protection of power generators for industrial or special applications. The basic mode of operation are selected by a key switch. To turn off the BE124 generator control unit simply turn the key to off or remove the key. You can use the key to start the engine manually. Two push buttons are provided to control the AUTO mode and the Generator Circuit Breaker, Despite the complex technology inside Be124, the controller is user-friendly. The BE124 generator control unit integrates a 3-phase multi-function protection relay, an Earth Fault relay, an engine protection module, a multi-priority handler AUTO START module, SAEJ1939 compatible port, RS485 MODBUS-RTU port, multi-function I/O board, high performance rotational speed programmable relay. The Be124 generator control unit comes with factory settings, but you can adjust the hundreds of settings at any time, locally or by remote. This generator control unit interfaces with digital or analog sensors as well. All parameters are very well organized in menus. The graphic display provides helping messages to make the use of the controller intuitive. Because of the multi-processor architecture, this generator control unit provides embedded DATA LOGGER, OSCILLOSCOPE and 500 LOG EVENT REGISTER that works in conjunction with a real time clock independent from the battery engine. You can add external module to interface with GSM modem, TCP-IP server and MODBUS systems. The Be124 is shock proof and features an IP62 ingress protection. It is enclosed in a policarbonate enclosure 96mmx96mm.



This generator control unit features extraordinary auto start capabilities. It can automatically start the engine in the following situation:

1)  You have programmed the scheduler. You have at your disposal the possibility to program hour and minutes to start and stop the generator in every day of the week.

2) You start / stop the engine from a remote location by using a direct MODBUS communication [7], by using your mobile phone or via Internet. In this case the Be124 it is connected to a TCP-IP server.

3) You activate an input programmed with the AUTO START function [8]. You can set up delays and the type of contact: normally open or closed.

4) You programmed the AUTO START to recharge the battery of the engine [6]. The engine will stop when the battery are fully charged or after a time out .

The connections of the Be124 are simple. The Be124 energize a fuel solenoid [2] and a start pilot relay [3] &[4]. The start relay will crank the engine via the crank-motor [5]. The Be124 terminates the crank when the belt alternator [1] provides the proper voltage. Be124 will terminate the crank when voltage/frequency/speed are over certain limit.


Generator Control Unit 3-phase protection relay

This generator control unit is a compact 3-phase protection relay. All protections are programmable: Over/Under V, Over/Under Hz, Phase unbalance, Reverse Power, Over Current, Over Load, Short-Circuit. The relay works up to 600 Hz. You can use the Be124 with 400Hz generator. You can monitor the Earth Fault current and you can set a limit to trip the generator.  To understand better the all parameters you can watch the video about


In case of doubts you can use the embedded generator control unit oscilloscope to display the wave-forms of the voltage and currents. You can track the power every second up to days by using the embedded DATA logger. The Be124 counts the energy (kWH) and is able to display all parameters of the 3-phase system.


The Be124 generator control unit display all electrical parameters on a graphic display. The generator instruments are organized in pages. You can use a remote computer to get a better view of the instruments. The pages of the generator control unit are not static. The micro controller automatically displays the pages according to what the generator is doing. You have, anyway, a manual control of the display by using four arrows.

Generator Control Unit SAEJ1939 CANbus

The generator control unit features a CANBUS [2] port that supports the SAE J1939 standard. The port is fully isolated  from the engine battery. This will increase the reliability of the system. The Be124 contains a menu with the list of the most popular engine: Deutz, Volvo, Scania, Perkins , etc. Via CANBUS you can control the nominal speed and idle speed. The Be124 supports all alarms provided by the ECU. These alarm can be sent to your mobile phone or to a remote computer via Internet.

Generator Control Unit Modbus Remote Control Monitoring

The Be124 generator control unit is extremely flexible on remote control & monitoring. The Be124 provides a serial interface RS485 [1] that support the MODBUS-RTU protocol.  You will be able to communicate with Be124 via Internet by using the TCP-IP server.  You can control the generator with short messages by using the BE16 GSM SMS generator. In factory automation system you can integrate the emergency generator by assigning a node address to the generator control unit.


 Generator Control Unit Remote Monitoring

A generator control unit like Be124 is higly recommended when you need a fail-safe remote monitoring system. The TCP-IP server supplied as optional module to this generator control unit converts the MODBUS protocol into MODBUS over TCP-IP. In the same time, this module, being a server, it creates a virtual site for the generator. Your generator is seen as a web site by assigning a public IP address. This means that once your credentials are approved, you can use internet to interact with your emergency generator. You can remotely start and stop the engine, you can adjust the settings as well. The major advantage is that you are the proprietor of the server. You do not only purchase a 'Protocol Converter'.  You create a sort of domain for your emergency generator by purchasing a TCP-IP server. You are not required subscribing special services or pay royalties. You do not need antivirus because the system uses the most advanced encrypted communication technology.  Only you can pay access to your generator control unit via WEB. This is the most professional solution available on the market today. In case of troubles to the server [2], the generator control unit [2] will continue to work. Any troubles to the routers [6] or [3] or to the peripheral devices [4] [5] [7] [8] will not affect the main job of your emergency generator. In case of sever damage of the communication systems (due to lightning for example) you will not require to replace the generator control unit.


 Generator Control Unit Under Speed Protection

The under speed protection is one of the most complex and misunderstood generator control unit protection. Seems easy to say: simply stop the engine when the speed falls below this limit. It is not simple as it seems. When It is about shutting down an engine working in critical environment you have to take care. Let’s see some details. The Be124 generator control unit monitors simultaneously frequency (Hz), rotational speed (RPM), electrical load (KW) and generator voltage (V). These  measurements are included into a mathematical  algorithm. The final result is to provide an immediate shutdown, a shutdown after a delay or a simple warning.

The mathematical formula is able to understand if it is an overload conditions or a mechanical failure.  The picture shows an example of an overload condition. After a start, the engine reaches its nominal speed [1]. The ‘WARM UP’ time takes place when Rotational Speed (RPM)/Voltage(V)/Frequency(Hz)/Sequence (PS)/Phase Balance(PB) are within preset-limits.

Should a parameter exit the allowed range, the Be124 will reset the warm-up time. The timer will restart only when all parameters will be within the limits. Warm setting can range from zero up to several minutes. When a failure occurs, the engine will stop. The Be124 will provide the alarm 'GENERATOR FAILURE'.

Supposing  that everything is OK, the generator circuit breaker will automatically close [2]. Let’s assume now that speed RPM decreases down below the lower limit. The 'Bypass Delay' timer will start to count and, if the speed returns normal the Be124 will reset the timer. If after expiring the timer the Be124 detects a speed lower than the allowed setting, the Be124 will open the circuit breaker providing the alarm 'UNDER SPEED' [4].

The engine will not be stopped immediately because, in the formula, the power parameters plays the most important role! In this way, the 'Cooling Down' time will take place. Then, the engine will be stopped.

Generator Control Unit Under Speed Protection
 Understanding Crank Termination Using Of Generator Control Unit

Crank termination is an adjustable engine speed setting that shuts down the starter motor when the engine is firing and the cranking must be terminated.  The output of the generator control unit drives a pilot relay. The pilot relay will de-energize in order to stop the current flow to the starter motor circuit when the engine crank termination setting is reached. The starter motor pinion gear will then disengage from the engine flywheel ring gear.

The theory is not so complex. Unfortunately there are many ‘volatile’ parameters involved when you crank an engine: status of the battery, aging of the starter motor, ambient temperature, difficulties in starting the engine due to mechanical problems, unstable connections and so on. When it is about manual switch start, you will find soon or later the problem and finally you will start the engine.

The hard job of the Be124 generator control unit is to analyze many sources of information way to start the engine automatically.  As a matter of fact it monitors: the charger alternator voltage (V), the charger alternator frequency (Hz), the generator alternator voltage (V) & frequency (Hz), the rotational speed of the engine (RPM). For each parameter the Be124 features programmable settings that include the option OFF (in other words Be124 does not take in consideration a parameter set to ‘OFF). It is obvious that the most accurate rotational speed (RPM) information is provided by a pickup. Unfortunately not all engines have this device.

It is about a permanent magnet generator with a single pole. Wire coils are wounded around a permanent magnet pole piece. When the teeth of the flywheel ring gear moves through the magnetic lines of force that are around the magnetic pickup pole  an AC voltage is generated.  Engine speed is measured by the frequency of the signal generated by the pickup.  You can program the number of teeth of the ring gear in a way to get the  correct rotational speed).  When Be124 starts the engine, a software routine continuously compares in real-time the settings with the parameters (voltages, frequencies, etc). Once at least two signal are recognized as ‘true’, the Be124 terminates the crank.