The A.SRA20 device connected to Guard Evo. allows the customer to remotely set off alarm, pre-alarm or operating mode signals for the generating set through the contacts of the 20 relays equipped with suitable cabling and system. It is possible to control lights and sounds or interface with supervision systems, such as a PLC for example, based on the requirements of the final user.


The device is equipped with 20 relays, all with volt-free contact (2A- AC1 max 50Vdc), cabled in a PCB to dedicated terminal blocks, with a led associated to each relay highlighting the status of the contact. On the circuit, in addition to the power supply terminals, there is an RS485 port for the connection with Guard Evo. and an RS232 port for the connection to a PC, the acquisition and processing the signals from Guard Evo. and the management of the relays is carried out through a dedicated microprocessor. The A.SRA20 device was designed to be installed near the equipment where the customer wishes to carry out supervision, while the connection with the Gen. set is carried out through two conductors that are connected to the RS485 port. This allows the cables to be set up in the best possible manner and to contain costs.

The connection between Guar Evolution and the A.SRA20 device through RS485 is 1 km at most. The A.SR20 device can be powered at 12 or 24V regardless. The power supply can be connected to the battery on the generating set. In this case it is necessary to make sure that the consumption is acceptable by the load maintenance systems, or by a different source that is always on (the power supply must be constant, otherwise communication will be lost in case of momentary power shortage). The maximum absorption of the device is 15 VA. All of the relays have volt-free contacts (2A- AC1 max 50Vdc).


Each relay is associated to a function corresponding to the standard configuration (20 ALL 00 - '20 ALARMS 00') reported below. On request different functions from those envisioned can be associated with the relays, for a maximum of 20; the minimum overall dimensions are only 235mm x 125 mm;

Relay 1 Mains contactor control on (System status)
Relay 2 Genset contactor control on (System status)
Relay 3 Engine running (System status)
Relay 4 Cumulative general fault (Alarm)
Relay 5 Emergency button pressed (Alarm)
Relay 6 Generator tension not correct (Alarm)
Relay 7 Mains tension not correct (Alarm)
Relay 8 Engine running at low rpm (Alarm)
Relay 9 No ignition (Alarm)
Relay 10 Battery charger alternator not energised (Alarm)
Relay 11 Mechanical engine stop (Alarm)
Relay 12 Minimum engine oil pressure (Alarm)
Relay 13 Maximum engine temperature (Alarm)
Relay 14 Minimum radiator liquid level (Alarm or Pre-alarm)
Relay 15 Minimum fuel level (Alarm or Pre-alarm)
Relay 16 Cumulative general pre-alarm (Pre-alarm)
Relay 17 Minimum battery tension (Pre-alarm)
Relay 18 Maximum battery tension (Pre-alarm)
Relay 19 Maintenance request (Pre-alarm)
Relay 20 Generating set not in AUTOMATIC (System status)