1. The display on coal feeding meter on DCS decreases or becomes zero or fixed. 

2. The display of oxygen gauge increases. 

3. When the temperature of main steam decreases, the steam pressure drops, the coal feeding interruption time is longer and broken coal for a long time, the bed temperature drops.

4. If the boiler steam temperature drops, the steam pressure drops and the load decreases. 

Causes: 

1. The coal feeder is stuck; There are sundries in the coal that block the coal; The motor is idling. 

2. The  coal in the raw coal bunker  is too wet, thus  the coal is arching.

Treatment: 

1. properly increase the coal feeding amount of other operating coal feeder. 

2. Immediately open the vibrator on the warehouse wall to rap the coal bin and coal drop pipe or change the pin. 

3. If the coal feeding to the three coal feeders is interrupted, and it still cannot recovered after the above measures have been taken, the boiler shall be temporarily banked up. And the measures shall be taken as soon as possible to eliminate the faults.