schematic knowledge

An overload condition in an inverter may  permanently  damage  the  power transistor array or burn off the transformer. Some of the domestic inverters sold in the market do not feature an overload shutdown facility, while those incorporating this feature come with a price tag.the circuit presented here is an overload detector which shuts down the inverter  in  an  overload  condition. 

It  hasthe following desirable features:

The circuit uses an ammeter  (0-30a)  as  a  transducer  to  detect  overload condition.  Such  an  am-meter  is  generally  present in  almost  all  inverters.  this  ammeter  is connected between the negative supply of the battery and the inverter, as shown in Fig. 2. the voltage developed across this ammeter, due to the flow of current, is very small. It is amplified by IC2, which is wired as a differential amplifier having a gain  of 100. IC3 (NE555) is connected as a Schmitt ‘trigger’, whose output goes low when the voltage at its pin 2 exceeds 3.3V. IC4 (again an NE555 timer) is configured as  a  monostable  multivibrator  with  a pulsewidth of 6 seconds. IC5 (CD4017) is a CMOS counter which counts the three overload  conditions,  after  which  the  sys-tem has to be reset manually, by pressing push-to-on switch S1. the  circuit  can  be  powered  from  the inverter battery. In standby condition, it consumes 8-10 ma of current and around 70 mA with relay (RL1), buzzer (PZ1), and LED1 energised.