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)

BATTERY

Capacity of battery is denoted by Amp/hour. = Capacity x hour

                             V-Eb

Cell current (I) =--------

                            R + r

Where V= Emf, Eb = Bach emf, R= outside resistance, r= Internal resistance

Battery charging current = Capacity/hours. *cell charging current should be applied as per manual.

Equalizing Charging: Charge on low rate. Charge up to three same reading of voltage & sp. Gravity.

Battery drawback:

Sulfation:   Active material in the form of sulfur, deposits on +ve & -ve plate and surface of plate is hardened.

Plates buckling: At the time of charging/discharging if it is taking high current then its temperature will also increase. Due to this, plates get bending un-uniformly and there is a possibility of short ckt.

Sensitization: In battery, active material is depositing on the plates. An active material, in the form of powder form deposited at the bottom of cell. So internal resistance of the cell increases and battery loose its capacity.

Ni – Ca Battery Chemical Reaction

+ve Plate: Nickel hydroxide as the active constituent.

-ve Plate: Cadmium hydroxide

Electrolyte: Solution of Potassium hydroxide in DM water with lithium hydroxide as an additive.

2Ni(OH)₃ + 2Cd(KOH)   -> 2Ni(OH)₂ + 2Cd(OH)₂ + 2KOH

The Potassium hydroxide electrolyte takes no parts in these reactions and acts only as a carrier of ions and the lithium hydroxide additive in the electrolyte significantly increases the life of the cell since it has a beneficial effect on the positive electrodes. This beneficial effect is more.

UPS A BATTERY: 350A/h (a) C-10 (T350P) 2V per cell, 180 cells.

UPS B BATTERY: 200 A/h (a) C-10, 12v, 32 CELLS

CABELING REQUIREMENTS

Planning cable runs

·         Use the shortest possible motor cable lengths.

·         Use a single length of cable to a star junction point to feed multiple motors.

·         Keep electrically noisy and sensitive cables apart.

·         Keep electrically noisy and sensitive parallel cable runs to a minimum. Separate parallel cable runs by at least 0.25 metres. For runs longer than 10 metres, separation should be increased proportionally. For example if the parallel runs were 50m, then the separation would be (50/10)x0.25m.

·         Sensitive cables should cross noisycabes a 90⁰ .

·         Never run sensitive cables close or parallel to the motor, dc link and braking chopper circuit for any distance.

·         Never run supply, dc link or motor cables in the same bundle as the single/control and feedback cables, even if they are screened.

·         Ensure EMC filter input and output cables are separately routed and do not couple across the filter.

INCREASING MOTOR CABLE LENGTH

Because cable capacitance and hence conducted emission increase with motor cable length, conformance to EMC limits is only guaranteed with the specified ac supply filter option using a maximum cable length as specified .

This maximum cable length can be improved using he specified external input or output filters.

Screened/armored cable has significant capacitance between the conductors and screen which increases linearly with cable length (typically 200pF/m but varies with cable type and current rating).

LONG CABLE LENGTHS MAY HAVE THE FOLLOWING UNDESIRABLE EFFECTS;

Ø  Tripping on ‘Over current’ as the cable capacitance is charged and discharged at the switching frequency.

Ø  Producing increased conducted emissions which degrade the performance of the EMC filter due to saturation.

Ø  Causing RCDs (Residual Current Devices) to trip due to increased high frequency earth current.

Ø  Producing increased heating inside the EMC ac supply filter from the increased conducted emissions.

These effects can be overcome by adding chokes or output filters at the output of the VSD.

STAR POINT EARTHING:

A star-point earthing policy separates ‘noisy’ and ‘clean’ earths. Four separate earth bus bars (three are insulated from the mounting panel) connect to a single earth point (star point) near the incoming safety earth from the main supply. Flexible, large cross-section cable is used to ensure low HF impedance. Bus bars are arranged so that connection to the single earth point is as short as possible.

XLPE( CROSS LINGK POLLY ETHYLENE)

ADVANTAGE

1.      Conductor operating temperature : 90⁰C

2.      Short ckt withstand temperature    :250⁰C

3.      High current rating

4.      High di-electric strength

5.      Very low di-electric losses

6.      Due to high di-electric strength, size is less compared to other.

7.      Low weight, easy for laying, easy bending ie. 20⁰.

8.      Low water absorption.

9.      Low charging current

10.  Easy jointing procedure

11.  Fire retardant

COMPARISION BETWEEN XLPE AND PILCA

SN	XLPE	PILC
1	On load 900 C Temperature	On load 700 C temperature
2	Low weight	Heavy weight
3	Defuses moisture	Absorbs moisture
4	Short circuit temperature 2500C	Short circuit temperature is 1600C
5	Fire resistance - Fair	Fire resistance - poor

CABLE CODE:

1.      Copper conductor                               --

2.      Aluminum conductor                          A

3.      PVC sheath & insulation                     Y

4.      Steel round wire armor                      W

5.      Steel strip armor                                 F

6.      Steel double round wire armor          WW

7.      Steel double strip armor                     FF

GENERAL TECHNICAL DATAS FOR 33KV(E) 400 sq mm XLPE CABLE

SN	DETAILS	Data
1	Name of manufacturer & address of work	Polycab wires Pvt. Ltd, HICCL, 1st fl, 731, Pandit Satwalkar marg, Mahim, Mumbai-400016
2	Applicable standard	IS:7-98(para II)1985 with latest amendments.
3	Voltage grade	33KV(E)
4	Conductor temperature at rated current	900C
5	Max. temperature during short circuit under hot condition	2500C
6	No. of cores	3
7	Cross section area of conductor	400 sq mm
8	Conductor material, hardness & conductor flexibility class	Aluminum H2/H4 grade, class II IS:8130/84
9	No. & diameter of conductor stands	57 strands, 3.06 dia
10	Shape of conductor	Compact, circular
11	Material & min. thickness of conductor screening	Extruded semi conducting compound of 0.30 mm thickness
12	Insulation material composition	Extruded XLPE
13	Min. & normal thickness of insulation	7.82mm (minimum)
14	Max. electric stress on the conductor screen	30 – 35 KV/mm
15	Material, min. thickness type of non-metallic insulation screening	Free strippable with stripper extruded, semi conductor compound of 0.30 mm thickness.
16	Material, min. thickness & width of metallic screen	Copper type 30 x 0.05 mm
17	Filler material	Suitable PVC compound
18	Min, thickness & material of inner sheath	0.70 mm, extruded PVC compound type ST-2

COMPARISION BETWEEN XLPE, PVC, PILC

SN	DATA	XLPE	PVC	PLIC
1	Specific Gravity	0.93	1.35,1.46	1.1
2	Electric loss factor(Temp. 200C)	0.0004	0.07	0.003
3	Volume resisting area 200C Aluminum & Copper	1117	1010-1015	1015
4	Max permissible operating continue temperature	900C	700C	650C
5	Max permissible short circuit temperature	2500C	1600C	1600C
6	Short time O/L temperature	1300C	1200C	800C
7	Dielectric constant at 200C	2.35	6-8	3-5
8	Power Factor at max. conducting temperature	0.008	0.1	0.01
9	Impulse level volts/min	2000	1100	1800
10	Thermal resistivity  0C/Con/Watt	350	650	550
11	Partical discharge picl con/m3	5	40	--

If = Ish/√t             Where It – Short ckt rating for 1 sec

                                             t – directional in sec

                                             Ish – Short ckt ratio for 1 sec

CLASSIFICATION OF POWER SUPPLY

1.      Class IV           - Normal PS 415V 3 ph – 2500 KVA

2.      Class III – Diesel Generator setm 415V, 3 ph, 1010KVA – Self exited.

3.      Class II   - UPS – 230V, 50 KVA

4.      Class I    - Battery pS – 110VDC, 550AH & 425 AH-ROP S/stn, 300 AH – PREFRE S/stn.

Class I – Control ckt VCB, Exit lighting

Class II – Control room all area monitors, SCADA, trx scanners.

Class III – E2 fans & lighting

Class IV – All are normal supply.

FRLS: Flame Retardant Low Smoke Cable: Used in High block