8-Channel Fuse Failure Indicator cum Annunciation System

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In power utilities like TSSPDCL, it is a regular practice in 33/11KV indoor and outdoor substations that various electrical equipments like HV breaker, LV breaker, feeder breaker, battery charger, etc., are supplied with AC/DC supply through fuses.  Substation operators are instructed by in-charge officers to regularly monitor the availability of power supply to these equipments through indicating bulbs, healthy trip circuits, trip supervision circuits, toggle switches, etc.  But, most of the operators hardly check these power supplies to equipment.  Sometimes indicating bulbs and meters do not function.

Protection equipment like circuit breakers will not function on non-availability of DC supply, which will not trip on faults and cause damage to equipment under protection.  This will results in tripping of backup protection equipment i.e., pulling out LV breaker or pulling out breaker at EHT substations, causing unnecessary interruption to more number of consumers. If  this failure of fuse is recognized by the operator in advance by some proper indication and annunciation system these kind of interruptions can be avoided and also burden of MRT staff coming from distance location for replacing the fuse  and CBD staff arranging back feed to the feeders will be eliminated.

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Reduction of 11KV Interruptions – Middle Phase Raising

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A typical V-Cross Arm is as follows……

V Cross Arm

This is the actual design to be adopted for stringing of 11KV HT lines.
This pattern avoids bird faults, touching of Phase to Phase lines, foreign material falling on lines and twisting of lines.
The V–Cross Arm Pattern is not being used in Urban Areas due to clearance problem from the buildings. Instead Horizontal Side Arm is used. Continue reading

Need for Heater Failure Alarms in Indoor Sub-stations

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In general all the 33/11KV Indoor substations with ABB, Siemens, Schneider Electric, etc breakers, are provided with heaters in each breaker compartment to avoid absorption of moisture by current transformers, cable end- terminations, epoxy bus insulators etc., during winter and rainy seasons so that good IR values are maintained between phase to phase and phase to neutral to avoid short circuits.

The Operators at substations are switching on the heaters only on specific instructions.  Though Operator switches on the heater, he/she is not sure whether the heater is functioning, as these heater circuits are not provided with any indicator bulbs and or alarms indicating functioning of heaters.

During rainy and winter seasons if heaters fail to function, current transformers absorbs moisture formed inside the breaker compartments and create dead short circuit on 33KV and 11KV cable feeders.

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Active Power Control on Transmission Lines

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Power flow on transmission lines needs to be controlled in order to achieve the optimum utilization of transmission lines capacity.

The distribution of the power flow between two parallel lines is dictated by their impedances.  The line with smaller impedance carries more power and vice versa.

The active power and reactive power over a transmission line is given by,
Slide1

Where, VS  is sending end voltage
.   Vis receiving end voltage
.   XL is line impedance
.   δ is power angle (angle between sending end and receiving end voltages)
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Non-Contact Voltage Tester – Handy Device to Reduce Electrical Accidents

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Most of the electrical accidents are occurred due to one common reason – Persons DIRECTLY working on LIVE LINES without discharging live electrical lines using earth discharge rods.

In day to day operations and maintenance works, if supply status in these lines are detected before touching them, most of such electrical accidents can be avoided.

Non-Contact Voltage Tester with Buzzer and/or LED light is best suited and some of such products are as follows…

KUNDIP Series – Hi-Tech Advanced Tester (as below)

Voltage Tester1 Continue reading

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