Cable & Busbar Sizing interview questions

1. A.Indian code of practice for installation and maintenance of power cables up to 33 kV, covering laying depth, bending radius and jointing
2. B.IS 1554 covers PVC-insulated power cables up to 1.1 kV; IS 7098 covers XLPE cables, Part 1 up to 1.1 kV and Part 2 for 3.3–33 kV
3. C.cable sized so the drop from source to load at full current stays within about 3% for lighting and 5% for power circuits
4. D.multipliers for ambient temperature, ground thermal resistivity, depth of laying and grouping whose product reduces the tabulated current rating

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1. A.IS 1255
2. B.XLPE vs PVC insulation
3. C.Busbar short-time withstand
4. D.Minimum bending radius

Answer + AI explanation with Pro

1. A.IS 1255 — cross-linked polyethylene allows 90 °C continuous conductor temperature and 250 °C short-circuit limit versus 70 °C and 160 °C for PVC
2. B.IS 1255 — IS 1554 covers PVC-insulated power cables up to 1.1 kV; IS 7098 covers XLPE cables, Part 1 up to 1.1 kV and Part 2 for 3.3–33 kV
3. C.IS 1255 — Indian code of practice for installation and maintenance of power cables up to 33 kV, covering laying depth, bending radius and jointing
4. D.IS 1255 — copper bars carry roughly 1.2–1.6 A/mm² and aluminium 0.8–1.0 A/mm² in ventilated enclosures before temperature-rise verification

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1. A.tray width chosen so cables occupy no more than about 40–50% of the tray with one-diameter spacing between power cables to preserve ratings
2. B.IS 1554 covers PVC-insulated power cables up to 1.1 kV; IS 7098 covers XLPE cables, Part 1 up to 1.1 kV and Part 2 for 3.3–33 kV
3. C.copper bars carry roughly 1.2–1.6 A/mm² and aluminium 0.8–1.0 A/mm² in ventilated enclosures before temperature-rise verification
4. D.cross-linked polyethylene allows 90 °C continuous conductor temperature and 250 °C short-circuit limit versus 70 °C and 160 °C for PVC

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1. A.XLPE vs PVC insulation
2. B.Busbar short-time withstand
3. C.IS 1255
4. D.Cable tray sizing

Answer + AI explanation with Pro

1. A.XLPE vs PVC insulation — about 12 times overall diameter for multicore XLPE power cables and 15–20 times for single-core HV cables during installation
2. B.XLPE vs PVC insulation — cross-linked polyethylene allows 90 °C continuous conductor temperature and 250 °C short-circuit limit versus 70 °C and 160 °C for PVC
3. C.XLPE vs PVC insulation — Indian code of practice for installation and maintenance of power cables up to 33 kV, covering laying depth, bending radius and jointing
4. D.XLPE vs PVC insulation — rated Icw such as 50 kA for 1 s verified by type test, with peak withstand Ipk about 2.1–2.2 times Icw for high fault levels

Answer + AI explanation with Pro

1. A.Indian code of practice for installation and maintenance of power cables up to 33 kV, covering laying depth, bending radius and jointing
2. B.IS 1554 covers PVC-insulated power cables up to 1.1 kV; IS 7098 covers XLPE cables, Part 1 up to 1.1 kV and Part 2 for 3.3–33 kV
3. C.cable sized so the drop from source to load at full current stays within about 3% for lighting and 5% for power circuits
4. D.about 12 times overall diameter for multicore XLPE power cables and 15–20 times for single-core HV cables during installation

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1. A.IS 1554 and IS 7098
2. B.IS 1255
3. C.Minimum bending radius
4. D.Derating factors

Answer + AI explanation with Pro

1. A.IS 1554 and IS 7098 — copper bars carry roughly 1.2–1.6 A/mm² and aluminium 0.8–1.0 A/mm² in ventilated enclosures before temperature-rise verification
2. B.IS 1554 and IS 7098 — cross-linked polyethylene allows 90 °C continuous conductor temperature and 250 °C short-circuit limit versus 70 °C and 160 °C for PVC
3. C.IS 1554 and IS 7098 — cable sized so the drop from source to load at full current stays within about 3% for lighting and 5% for power circuits
4. D.IS 1554 and IS 7098 — IS 1554 covers PVC-insulated power cables up to 1.1 kV; IS 7098 covers XLPE cables, Part 1 up to 1.1 kV and Part 2 for 3.3–33 kV

Answer + AI explanation with Pro

1. A.multipliers for ambient temperature, ground thermal resistivity, depth of laying and grouping whose product reduces the tabulated current rating
2. B.about 12 times overall diameter for multicore XLPE power cables and 15–20 times for single-core HV cables during installation
3. C.cable sized so the drop from source to load at full current stays within about 3% for lighting and 5% for power circuits
4. D.rated Icw such as 50 kA for 1 s verified by type test, with peak withstand Ipk about 2.1–2.2 times Icw for high fault levels

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1. A.Busbar short-time withstand
2. B.Voltage drop criterion
3. C.Busbar current density rule
4. D.Derating factors

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1. A.Derating factors — about 12 times overall diameter for multicore XLPE power cables and 15–20 times for single-core HV cables during installation
2. B.Derating factors — multipliers for ambient temperature, ground thermal resistivity, depth of laying and grouping whose product reduces the tabulated current rating
3. C.Derating factors — tray width chosen so cables occupy no more than about 40–50% of the tray with one-diameter spacing between power cables to preserve ratings
4. D.Derating factors — copper bars carry roughly 1.2–1.6 A/mm² and aluminium 0.8–1.0 A/mm² in ventilated enclosures before temperature-rise verification

Answer + AI explanation with Pro

1. A.rated Icw such as 50 kA for 1 s verified by type test, with peak withstand Ipk about 2.1–2.2 times Icw for high fault levels
2. B.tabulated list of every cable with tag, from/to, size, cores, length, route and gland type used for procurement and site pulling
3. C.minimum conductor area equals I·√t divided by k, with k about 143 for copper and 94 for aluminium XLPE (90 °C to 250 °C)
4. D.IS 1554 covers PVC-insulated power cables up to 1.1 kV; IS 7098 covers XLPE cables, Part 1 up to 1.1 kV and Part 2 for 3.3–33 kV

Answer + AI explanation with Pro

1. A.Busbar current density rule
2. B.Cable schedule
3. C.Voltage drop criterion
4. D.Short-circuit withstand of cable

Answer + AI explanation with Pro

1. A.Short-circuit withstand of cable — multipliers for ambient temperature, ground thermal resistivity, depth of laying and grouping whose product reduces the tabulated current rating
2. B.Short-circuit withstand of cable — IS 1554 covers PVC-insulated power cables up to 1.1 kV; IS 7098 covers XLPE cables, Part 1 up to 1.1 kV and Part 2 for 3.3–33 kV
3. C.Short-circuit withstand of cable — about 12 times overall diameter for multicore XLPE power cables and 15–20 times for single-core HV cables during installation
4. D.Short-circuit withstand of cable — minimum conductor area equals I·√t divided by k, with k about 143 for copper and 94 for aluminium XLPE (90 °C to 250 °C)

Answer + AI explanation with Pro

1. A.IS 1554 covers PVC-insulated power cables up to 1.1 kV; IS 7098 covers XLPE cables, Part 1 up to 1.1 kV and Part 2 for 3.3–33 kV
2. B.copper bars carry roughly 1.2–1.6 A/mm² and aluminium 0.8–1.0 A/mm² in ventilated enclosures before temperature-rise verification
3. C.multipliers for ambient temperature, ground thermal resistivity, depth of laying and grouping whose product reduces the tabulated current rating
4. D.cable sized so the drop from source to load at full current stays within about 3% for lighting and 5% for power circuits

Answer + AI explanation with Pro

1. A.Voltage drop criterion
2. B.Derating factors
3. C.Busbar current density rule
4. D.Busbar short-time withstand

Answer + AI explanation with Pro

1. A.Voltage drop criterion — minimum conductor area equals I·√t divided by k, with k about 143 for copper and 94 for aluminium XLPE (90 °C to 250 °C)
2. B.Voltage drop criterion — tabulated list of every cable with tag, from/to, size, cores, length, route and gland type used for procurement and site pulling
3. C.Voltage drop criterion — cable sized so the drop from source to load at full current stays within about 3% for lighting and 5% for power circuits
4. D.Voltage drop criterion — tray width chosen so cables occupy no more than about 40–50% of the tray with one-diameter spacing between power cables to preserve ratings

Answer + AI explanation with Pro

1. A.copper bars carry roughly 1.2–1.6 A/mm² and aluminium 0.8–1.0 A/mm² in ventilated enclosures before temperature-rise verification
2. B.Indian code of practice for installation and maintenance of power cables up to 33 kV, covering laying depth, bending radius and jointing
3. C.tabulated list of every cable with tag, from/to, size, cores, length, route and gland type used for procurement and site pulling
4. D.tray width chosen so cables occupy no more than about 40–50% of the tray with one-diameter spacing between power cables to preserve ratings

Answer + AI explanation with Pro

1. A.IS 1554 and IS 7098
2. B.Busbar short-time withstand
3. C.Cable schedule
4. D.Voltage drop criterion

Answer + AI explanation with Pro

1. A.Cable schedule — tray width chosen so cables occupy no more than about 40–50% of the tray with one-diameter spacing between power cables to preserve ratings
2. B.Cable schedule — tabulated list of every cable with tag, from/to, size, cores, length, route and gland type used for procurement and site pulling
3. C.Cable schedule — cross-linked polyethylene allows 90 °C continuous conductor temperature and 250 °C short-circuit limit versus 70 °C and 160 °C for PVC
4. D.Cable schedule — IS 1554 covers PVC-insulated power cables up to 1.1 kV; IS 7098 covers XLPE cables, Part 1 up to 1.1 kV and Part 2 for 3.3–33 kV

Answer + AI explanation with Pro

1. A.multipliers for ambient temperature, ground thermal resistivity, depth of laying and grouping whose product reduces the tabulated current rating
2. B.copper bars carry roughly 1.2–1.6 A/mm² and aluminium 0.8–1.0 A/mm² in ventilated enclosures before temperature-rise verification
3. C.tray width chosen so cables occupy no more than about 40–50% of the tray with one-diameter spacing between power cables to preserve ratings
4. D.minimum conductor area equals I·√t divided by k, with k about 143 for copper and 94 for aluminium XLPE (90 °C to 250 °C)

Answer + AI explanation with Pro

1. A.Voltage drop criterion
2. B.Busbar short-time withstand
3. C.Cable tray sizing
4. D.IS 1255

Answer + AI explanation with Pro

1. A.Cable tray sizing — cable sized so the drop from source to load at full current stays within about 3% for lighting and 5% for power circuits
2. B.Cable tray sizing — tray width chosen so cables occupy no more than about 40–50% of the tray with one-diameter spacing between power cables to preserve ratings
3. C.Cable tray sizing — copper bars carry roughly 1.2–1.6 A/mm² and aluminium 0.8–1.0 A/mm² in ventilated enclosures before temperature-rise verification
4. D.Cable tray sizing — minimum conductor area equals I·√t divided by k, with k about 143 for copper and 94 for aluminium XLPE (90 °C to 250 °C)

Answer + AI explanation with Pro

1. A.rated Icw such as 50 kA for 1 s verified by type test, with peak withstand Ipk about 2.1–2.2 times Icw for high fault levels
2. B.tray width chosen so cables occupy no more than about 40–50% of the tray with one-diameter spacing between power cables to preserve ratings
3. C.tabulated list of every cable with tag, from/to, size, cores, length, route and gland type used for procurement and site pulling
4. D.about 12 times overall diameter for multicore XLPE power cables and 15–20 times for single-core HV cables during installation

Answer + AI explanation with Pro

1. A.Voltage drop criterion
2. B.Derating factors
3. C.Minimum bending radius
4. D.IS 1255

Answer + AI explanation with Pro

1. A.Minimum bending radius — about 12 times overall diameter for multicore XLPE power cables and 15–20 times for single-core HV cables during installation
2. B.Minimum bending radius — minimum conductor area equals I·√t divided by k, with k about 143 for copper and 94 for aluminium XLPE (90 °C to 250 °C)
3. C.Minimum bending radius — tray width chosen so cables occupy no more than about 40–50% of the tray with one-diameter spacing between power cables to preserve ratings
4. D.Minimum bending radius — cable sized so the drop from source to load at full current stays within about 3% for lighting and 5% for power circuits

Answer + AI explanation with Pro

1. A.tabulated list of every cable with tag, from/to, size, cores, length, route and gland type used for procurement and site pulling
2. B.rated Icw such as 50 kA for 1 s verified by type test, with peak withstand Ipk about 2.1–2.2 times Icw for high fault levels
3. C.cross-linked polyethylene allows 90 °C continuous conductor temperature and 250 °C short-circuit limit versus 70 °C and 160 °C for PVC
4. D.cable sized so the drop from source to load at full current stays within about 3% for lighting and 5% for power circuits

Answer + AI explanation with Pro

1. A.Busbar short-time withstand
2. B.Cable tray sizing
3. C.IS 1255
4. D.Derating factors

Answer + AI explanation with Pro

1. A.Busbar short-time withstand — rated Icw such as 50 kA for 1 s verified by type test, with peak withstand Ipk about 2.1–2.2 times Icw for high fault levels
2. B.Busbar short-time withstand — IS 1554 covers PVC-insulated power cables up to 1.1 kV; IS 7098 covers XLPE cables, Part 1 up to 1.1 kV and Part 2 for 3.3–33 kV
3. C.Busbar short-time withstand — Indian code of practice for installation and maintenance of power cables up to 33 kV, covering laying depth, bending radius and jointing
4. D.Busbar short-time withstand — tabulated list of every cable with tag, from/to, size, cores, length, route and gland type used for procurement and site pulling

Answer + AI explanation with Pro