PRESENTATION BY Mr.S.DAISON STALLON AP/EEE NEHRU INSTITUTE OF ENGINEERING AND TECHNOLOGY COIMBATORE.9489745477

1. SLIP POWER RECOVERY
SCHEME
PRESENTEDBY
MR.S.DAISONSTALLON Mtech,mba(phd)
AP/EEE
NIET

3. •It is used to control the speed of the
slip ring induction motors.
•The speed control of the IM can be
obtained either above or below
synchronous speed.
•Stator voltage control and rotor
resistance control have poor efficiency
at low speed range and suitable for
limited applications.

4. •In order to improve the performance
of the system like efficiency and
capacity of the drive.
•If the slip power of the SRIM can be
returned to the supply systems.
•Thus the over all efficiency can be
increased.

5. Slip power recovery scheme types
• KRAMER DRIVE
• SCHERBIUSDRIVE
• FURTHER CLASSIFIEDINTO
• CONVENTIONALSLIPPOWERRECOVERYSYSTEM
• STATICSLIP POWERRECOVERY SYSTEM

6. KRAMER SLIP POWER RECOVERY SYSTEM
•This type is used to control the
speed of an IM below rated speed.
•This can be obtained by either
conventional or static.
•Conventional Kramer drive system
•Improved Kramer drive system
•Static Kramer drive system

8. • This type consists of
• SRIM,DC MOTOR,ROTARY CONVERTER.
• The slip ring of the SRIM is connected to the input
of the rotary converter.
• It converter AC into DC voltage and fed to the DC
motor terminals.
• The DC motor shaft is connected with the shaft of
the SRIM.
• The DC Motor shaft is connected with the shaft of
the SRIM.

9. • The Speed of the SRIM is controlled by varying field
regulator of the DC Motor.
• The field regulator is connected separate DC bus.
• This type is also known as CONSTANT POWER
CONTROL.
• In case if rotory converter is overexcited, it will take
leading current which compensates for the lagging
current draw by SRIM.
• Hence power factor of the system can be improved.
• This type is only preferred 4000 kw and above power
level.

10. Modified or improved Kramer system with
diode

11. Withthyristor or scr

12. • In this system the mechanical rotory converter is
replaced by 3 phase diode bridge rectifier.
• The slip power of the rotor is fed to the input of
the 3 phase diode bridge rectifier.
• It converts AC into DC and its ripple filtered by
series connected inductor.
• The filtered DC output voltage is fed DC motor
armature terminals.
• The DC motor shaft is connected with the shaft of
the SRIM.

13. • The Speed of the SRIM is controlled by varying
field regulator of the DC motor.
• The field regulator is connected with separate DC
bus.
• The control speed range is zero to around the
synchronous speed by varying firing angle of
thyristor.
• Diode is replaced by SCR for high power
applications.

14. Static type Kramer slip power system

15. • This system is very popular in large pump and fan
drives.
• Where range of speed control is limited near, but
below synchronous speed.
• This drive system is efficient but power converter
is very low.
• This system is also called constant-torque drive.

16. Speed –torque chara

17. Advantages
• This system of speed control is economical
because the rectifier and inverter only have to
carry the slip power of the rotor.
• Which is less than the input power to the stator
• Its quite simple and stable.