Answer :
To solve this problem, we need to understand what happens in a delta-wired three-phase electrical system when one of the heating elements is open (damaged or disconnected).
A delta connection in a three-phase system consists of three elements connected in a triangle-like shape. When one element becomes open, it greatly affects the circuit's resistance readings.
Here's a simple breakdown of what to expect:
1. Understanding Open Circuit in Delta Connection:
- When one element is open, there will be no conducting path through that element.
- This will result in the points connected to this open element showing infinite resistance when measured across.
2. Interpreting the Options:
- We're looking for a scenario where two measurements show infinite resistance because they involve the open element.
- The remaining measurement should show a finite resistance, as it involves two closed elements.
3. Evaluating the Given Options:
- Option a:
- [tex]\( L1 \)[/tex] to [tex]\( L2 = 22 \)[/tex] ohms
- [tex]\( L1 \)[/tex] to [tex]\( L3 = \text{infinity} \)[/tex] ohms
- [tex]\( L2 \)[/tex] to [tex]\( L3 = \text{infinity} \)[/tex] ohms
- Analysis: This option shows two readings with infinite resistance and one with a finite resistance of 22 ohms. This fits the expected pattern of having one open element.
- Option b:
- All readings are finite, which doesn't match an open condition.
- Option c:
- One reading is infinite, but not two, which doesn't fit an open element scenario.
- Option d:
- Shows one finite resistance and two infinite readings, but the finite resistance value is different (42 ohms, not 22 ohms).
Based on this evaluation, option a matches the expected resistance readings for a delta-wired system with one open element, as it accurately reflects two points showing infinite resistance due to the open element and one point showing a finite resistance. Thus, the correct answer is option a.
A delta connection in a three-phase system consists of three elements connected in a triangle-like shape. When one element becomes open, it greatly affects the circuit's resistance readings.
Here's a simple breakdown of what to expect:
1. Understanding Open Circuit in Delta Connection:
- When one element is open, there will be no conducting path through that element.
- This will result in the points connected to this open element showing infinite resistance when measured across.
2. Interpreting the Options:
- We're looking for a scenario where two measurements show infinite resistance because they involve the open element.
- The remaining measurement should show a finite resistance, as it involves two closed elements.
3. Evaluating the Given Options:
- Option a:
- [tex]\( L1 \)[/tex] to [tex]\( L2 = 22 \)[/tex] ohms
- [tex]\( L1 \)[/tex] to [tex]\( L3 = \text{infinity} \)[/tex] ohms
- [tex]\( L2 \)[/tex] to [tex]\( L3 = \text{infinity} \)[/tex] ohms
- Analysis: This option shows two readings with infinite resistance and one with a finite resistance of 22 ohms. This fits the expected pattern of having one open element.
- Option b:
- All readings are finite, which doesn't match an open condition.
- Option c:
- One reading is infinite, but not two, which doesn't fit an open element scenario.
- Option d:
- Shows one finite resistance and two infinite readings, but the finite resistance value is different (42 ohms, not 22 ohms).
Based on this evaluation, option a matches the expected resistance readings for a delta-wired system with one open element, as it accurately reflects two points showing infinite resistance due to the open element and one point showing a finite resistance. Thus, the correct answer is option a.
