Phenomenon: 

1. The instruction of voltmeter of 220 v thermal instrument reaches zero. 

2. All the indicating lamps of thermal meter are out. 

3. The instruction of thermal meter power is abnormal. 

4. The indication of resistance thermometer is back to zero and  the thermocouple  thermometer loses compensation. 

5. DCS control system is in outgage, the automatic adjustment control is abnormal and cannot operate. 

6. DCS control system is in failure, the electric signal output indicated in each position backs to zero (the indication of adjustment electric valve or the adjustment damper is fixed). 

7. DCS control system indicates failure, the opening indication of all valves and dampers is "0"and the indication of flow rate  etc.  is "0". 

Causes: 

1. 10 kV factory power interruption. 

2. 400 KV auxiliary power supply is interrupted. 

3. The switch of thermal meter power is in failure and trips. 

4. Thermal meter power is in outage and indication is abnormal. 

5. The automatic device of standby power source is in failure. 

6. The workers make wrong operation. 

Treatment: 

1. The back-up power supply for thermal meter shall be put into use immediately. 

2. If the back-up power supply for thermal meter cannot be put into use, it is required to report the shift chief-operator for recovering the power supply immediately. 

3. Contact  the operation personnel for steam turbine and electricity to stabilize the load. 4. Inform the thermal engineering personnel to rapidly manage and to recover the power supply . 

5. The control actuators for adjustment is changed from "automatic" to "manual", and the remote main power control is changed to the locally manual control. 

6. The local primary gauge is sued for monitoring the pressure of steam drum, pressure and temperature at outlet of superheated steam. 

7. The special personnel shall be assigned to monitor the local water level gauge of the steam drum and the walkie talkie is used for contacting the stoker to control the water level of steam drum. 

8.  It is required to frequently compare the steam turbine with the temperature, pressure of the superheated steam and to adjust them. 

9. The boiler in fault shall be kept stable as far as possible and the adjustment to it shall be reduced. 

10. In case of fault, it is prohibited to conduct regular blowdown, etc. 

11. After the power supply for 220 v thermal meter of boiler is recovered and the boiler is completely checked, the original operating mode shall be recovered, the local control is changed to remote control, each adjusting control actuators is changed from "manual" to "automatic". 

12. After the system power supply is on, the DCS control system cannot be "automatically controlled " again until the thermal engineering inspection personnel have inspected the system and confirmed it is in good condition. 

13. If the power supply cannot be recovered for a long time, then it is required to ask the leader for instructions on banking-up and stopping the boiler.