33KV PANEL RELAY PROTECTION

TYPE OF RELAYS

v  TRIV-VECTOR METER ELT

v  OVER VOLTAGE RELAY TYPE VIC

Definite time – ALStom – 50A (z)

v  INSTENSTENEUS UNDER VOLTAGE RELAY

Setting -> Type VAGM, 44 to 88 Volts

Connected Devices

1.      Cooling Tower Pump : Raw water tank Checking

2.      Cooling Tower Fan

3.      Air Compressor : 0 to 10 Kg/cm².

4.      Lub oil Priming pump :

5.      Fuel transfer pump

RELAYS USED FOR D.G. PANEL

1.      Restricted Earth Fault : Instantaneous Earth Fault – Type : CAG, Range : 1.5 to 4 Amps

2.      Negative phase sequence Relay: Negative sequence relay, Type: CTNM, Range:

3.      Earth fault relay: E/F relay(Inverse type) Type: CDG – Range: 0.5 to 2 Amps.

4.      Over Current Relay: (Inverse) Type: CDG- 3 NOS, Range: 2.5 to 10 Amps.

DG INCOMER PANEL

1.      Instantaneous Earth fault Relay: Type CAG, Range: 0.5 to 2 Amps

2.      Trip Circuit Supervision Relay: Type – VAX MK11, 110 – 125 Volts

3.      Definite Time Relay: Type VTT – 110V

4.      Over current Relay(Inverse)Type CDG, Range :2.5 to 10Amps

5.      Earth fault relay(Inverse) Type CDG, Range: 0.5 to 2 Amps

6.      Over current relay(Inverse) Type DCG, Range: 2.5 to 10Amps

7.      Tripping relay: Type VAG

PROTECTION FOR DG SET

SN	Alternator side		SN	Panel side
1	High Lub oil temperature		1	Over Voltage
2	High cooling water temperature		2	Over Current
3	Low lub oil pressure		3	Restricted Earth fault
4	Engine over speed		4	Under Voltage
			5	High winding temperature
			6	Bearing temperature

  HOW DG GETS ON

1.      In field exciter residual magnetism is available. When normal supply fails, command gets DG and 24VDC  Starter gets on, it rotates DG wheel & starter gets off. Due to this in the armature of exciter, EMF is produced.

2.      produced is 3 ph AC which converts in DC due to rotating diode assembly on the shaft and feed to rotating field.

3.      Main Rotating Field: This rotating field cuts stationary conductor of stator then EMF in is borne in stator coil.

4.      Stator Of Generator: Here exactly armature is given. But for brushless generator, it is constructed over stator, This is why no need of brush. Due to brushless, efficiency will be more.

When generator starts, it is on no-load, its field voltage is 32V & field current is 1.2 A & line voltage is 425V. When generator is loaded, its voltage should be decrease. But it do not take place because of Automatic Voltage regulator. When load increases, voltage getting to AVR, then exciter field winding voltage increases. There is no difference in voltage during loading, un loading. Speed is maintained by governor which increases diesel flow when speed decreases. 

AVR(Automatic Voltage Regulator) : The electronic controller is the heart of system which maintains stable output DC voltage of the charger in spite of supply voltage fluctuations and load variations.   

POWER FACTOR

It is a cosine angle between voltage & current.

In AC ckt Power factor is important because power of ckt is equal to a multiple of voltage, current & power factor. And if PF of ckt is lowered, current increases for the same load. Due to which it affects consumer & Energy supplying centre.

Losses due to low PF:  Due to low PF, current increases for the same load. Equipments use for power wiring, will be of higher capacity and increases its size. In installation, resistive load like incandescent lamp, heaters, hot plates which works on unity PF, gives low output. Again if PF of load decreased, current will increase for the same power so energy meter will run fast and we have to pay more bill even though we are using less power.

If PF of installation of more consumers is low, current of transmission line increases, voltage drops  & terminal voltage decreases. Due to which voltage regulation of generator at generation station is to be maintained regularly.  Due to increase in line current, generator gets overloaded and heated. Due to increase in line current, size of line conductor is also to be increased, span of line pole to be decreased & so number of line pole to be increased. Due to increase in number of poles, there is increase in accessories. It results increase in distribution charges. In this,  supply company suffers.

Advantage of High PF:

1.      It helps for stable terminal voltage

2.      Better voltage regulation

3.      Power losses between transmission & distribution line decreases

4.      Efficiency of generating station increases and transmission gets cheaper.

5.      Conductors & accessories do not get heated.

6.      No need to use higher capacity accessories.

 VECTOR GROUP

By this we can know that how winding is arranged (Displacement angle 11 or 1)

Slip =     N_S – N_R    X 100

                 N_S

1.      DOL Starter gives 100% torque

2.      Auto transformer starter gives 60 to 85% torque

3.      STAR DELTA starter gives 1/√3 times i.e 50% torque

4.      SOFT starter : Frequency constant, voltage not less than 40%

5.      VFD: Frequency & voltage can be reduced at a time. Smoothly speed varied.

CAPACITOR CONNECTIONS ARE IN PARALLEL:

Our load is inductive & so PF decreases. To improve PF,  we have added capacitor bank on 3 ph. In Delta, per capacitor 440 volts are getting. In star 440 volts between two capacitors. Means in Delta I_L = I_ph √3 and in Star I_L = I_ph.  If capacitance is more (I_c), for same PF Delta connection is require.

PROTECTION RELAY (CAPACITOR PANEL):

1.      Under voltage relay

2.      Over voltage relay

3.      Auxilary relay

4.      APFCR(Automatic Power failure control relay)