1. MUHAMMADALI MC SDE (KAM) KANNUR
SMPS AND POWER PLANT
MUHAMMADALI MC
SDE (KAM) KANNUR

2. Problems observed in conventional AC
Harmonics in the system
Standby is very difficult
Response to relays are poor
It is more hazardous

3. Conventional PowerPlant
Thyristors (SCR) used in Rectifier Circuit
Having Very Large size
Heavy weight
Low Efficiency
No scope for modular expansion
Not able to co-equip with technical room

4. Steps involved in Powerplant
Stepping Down the Input Voltage
Rectification
Filtering
Regulation
Stepping Down the Input Voltage is done by using STAR-DELTA Transformer. High voltage Low Frequency AC is converted into Low Voltage Low Frequency AC.

5. Rectification Normally for Rectification is done through,
Diode Rectifier
Bridge Rectifier
SCR Rectifier
SCR+Diode Rectifier
Through Diode : Ge type when volt exceeds 0.2 v
Si type when volt exceeds 0.7 v
The circuit is forward biased.
No control over the circuit

6. Through SCR: 1. Small gate current into the gate of the SCR to be triggered The gate current to be kept until the current through SCR reaches a point called Leaching Current Once SCR is turned ON, when the current through SCR reaches a limit called Holding Currrent, SCR will be turned off SCR have highest rating among Power Electronic Devices Low Turn ON Power requirement

7. The rectfication may be, Single Phase Half wave rectifier
Single Phase Full wave rectifier
Three Phase Half wave rectifier
Three Phase full wave rectifier
Filtering: Inductors & Capacitors are used
Inductors will conduct DC &
Capacitors will conduct AC
Regulation: I/P Volt +/- 12% variation
O/P Load 5% to 105% variation
Frequency +/- 4% variation

8. PowerPlant Components
Float Rectifier (FR)
Battery Charger (BC)
Switching Cubicle (SC)
It comes in three types,
Single Unit ie, FR, BC, SC together as single
Two Unit ie, FR/BC/SC + FR
Three Unit ie, FR, BC, SC separate

9. This can be again categarised as
Single Phase
5/ 12 A : Parallelling is not possible
25/ 50A : Manual Parallelling possible
Three Phase
>50 A : Auto Parallelling possible

10. Float Rectifier Float Voltage per cell is 2.15 v
Total Float Voltage is v
Components of FR
Step Down Transformer
Rectifier Circuit, Filters
Capacitor Bank : 1500 Micro Farad
Bleeder Resistance
Regulation Circuit

11. Important terms related with FR
Drooping: If the rated current > 105%, then
o/p volt suddenly reduced to 47 v
2. Psphometric Noise: <2mv if Bty connected
<4mv if Bty disconnected
3. Insulation Resistance : Min 5 Mega Ohm
4. Temperature : Limit 50 degree for system
Limit 45 degree for SCR
Limit 150 degree of BR

12. Pulse Transformer Card Amplifier Card Alarm Card
5.Discharge of Battery: When float volt reaches
49.2v or volt/cell 2.05v
6.Prioratisation: If load of priority > 90% rated
capacity, shared by others
Priority FR works on Constant Voltage and other Non Priorities works on Constant Current.
Cards In FR
Pulse Transformer Card
Amplifier Card
Alarm Card

13. Battery Charger Components of BC Step Down Transformer
Rectifier Circuit, Filters
Ballast Choke : To limit charging current
Output Voltage is 44 to 65 volts
Initial Charging 14% of rated capacity
Normal Charging 10hrs rate
This may be used as FR & Sick Cell charger

14. Switching Cubicle To connect three –ves of Battery To connect three FR
To connect three BC
To supervise Alarms
To do Auto parallelling
Here only one switch can be disconnected at a time , it is done by sollenoid control

15. Switch Mode Power Supply (SMPS)
Advantages:-
More Efficient
Economical
Safer
Compact in Size
Expansion is easier
Power Factor is improved
Can be co equipped with technical room

16. Categarisation of SMPS
I. Single Stage Conversion: Ii. Two Stage Conversion:
I/P AC SUPPLY (400V 50Hz)
STEPPED DOWN BY TRANSFORMER
RECTIFIED IN TO DC, FILTERING & REGULATION
I/P AC (400V50Hz)
RECTIFIER CKT
HIGH VOLT DC
HIGH FREQ CONVERTOR
STEP DOWN TR
RECTIFIER CKT

17. Classification of SMPS
Low Capacity Powerplant systems
To provide power to small telecome systems in
Rural, Semi Urban areas
Used with small system such as BTS in Urban
Works where building height is not upto std
(Height of SMPS rack is 1500mm)
6.25/ 12.5/ 25 Amp & 3phase 50 Amp
Battery Backup is high (6 to 72 hrs)

18. DSCA Unit of SMPS DSCA: Distribution, Switching, Control, Alarm
and Monitoring unit
1.Distribution & Switching:
Input Volt : 320 volt to 480 volt
Frequency : 45 Hz to 65 Hz
Autofloat Voltage : 54v (2.25v/cell) for VRLA
: 52.8v (2.2v/cell) for LA Battery
can be adjusted from 48 to 56 volts
Charging Voltage : 55.2 volt (2.30v/cell)
2.Control, Alm&Monitoring: MP based, menu driven
pgm; using RS485 bus

19. Physical Structure of SMPS
Racks : One Main Rack, One Auxillary, One Extension Rectifier Module : Max Two nos in Main & Aux Three nos in each extension AC & DC Distn module: In each rack Metering : In each rack Power System Controller: In main rack 9 Pin AC Socket AC & DC through terminals Control Signals through 8 pin Tel jack & terminated On PSC card (50 volts 5600 watts)

20. System Level Cards of SMPS
PSC Cards:
To generate all supervisory alarms
To monitor the status of rectifier modules
To monitor Bty path current & display status
Temco Cards:
Temperature compensation while Bty charging
Temp Gradient -72mv (3mv/cell) per degree celcius
Display & Alarm Cards:
Contains all Visual & audio alarms

21. System Level Alarms of SMPS
1. Mains on Battery Discharge 2. Battery Isolated 3. System Overload 4. Mains out of range 5. FR/ FC Fail 6. Temco Fail 7. Load Voltage Low 8. Load Voltage High 9. FR/ FC on Charge 10. Mains Available 11. FR/ FC on Float

22. Thank you