Water monitoring system and water monitoring method for high voltage cables
First Claim
1. A water monitoring system for a high voltage cable including at least one conductor and a screen surrounding said conductor, comprising:
- a1) a first water sensing wire extending in the screen between the cable beginning and the cable end;
a2) at least a second wire connected to the first water sensing wire at the cable end for forming a loop and extending from the cable end to the cable beginning;
b) a measuring circuit provided at the cable beginning and adapted to determine at least the occurrence of a water intrusion into the cable on the basis of voltage drop measurements at the first water sensing wire or the second wire;
c) a first switching unit between the cable beginning and the measurement circuit, said first switching unit being adapted to assume, in response to a first switching signal, a first switching state in which said first water sensing wire and said second wire are connected to a screen potential when the first switching signal has a first state; and
a second switching state in which said first water sensing wire and said second wire are disconnected from the screen potential when the first switching signal has a second state; and
d) a control unit adapted to output the first switching signal in the first state over a first predetermined time interval and thereafter to switch the first switching signal into the second state over a second predetermined time interval;
wherein e) said measurement circuit is adapted to perform said water intrusion measurement in said second predetermined time interval.
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Accused Products
Abstract
A water monitoring system and a water monitoring method for a high voltage cable including a conductor and a screen surrounding the conductor. At least a first water sensing wire extends in the screen between the cable beginning and the cable end and at least a second wire is connected with the first wire at the cable end to form a loop. A first switching unit is provided between the cable beginning and the measurement circuit. A control unit controls the first switching unit over a first predetermined time interval into a first switching state in which the water sensing wire and the second wire are connected to the screen potential. In a following second predetermined time interval the control unit controls the first switching unit into a second switching state in which the water sensing wire and the second wire are disconnected from the screen potential. The measurement circuit performs a water intrusion measurement in the second predetermined time interval.
21 Citations
20 Claims
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1. A water monitoring system for a high voltage cable including at least one conductor and a screen surrounding said conductor, comprising:
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a1) a first water sensing wire extending in the screen between the cable beginning and the cable end;
a2) at least a second wire connected to the first water sensing wire at the cable end for forming a loop and extending from the cable end to the cable beginning;
b) a measuring circuit provided at the cable beginning and adapted to determine at least the occurrence of a water intrusion into the cable on the basis of voltage drop measurements at the first water sensing wire or the second wire;
c) a first switching unit between the cable beginning and the measurement circuit, said first switching unit being adapted to assume, in response to a first switching signal, a first switching state in which said first water sensing wire and said second wire are connected to a screen potential when the first switching signal has a first state; and
a second switching state in which said first water sensing wire and said second wire are disconnected from the screen potential when the first switching signal has a second state; and
d) a control unit adapted to output the first switching signal in the first state over a first predetermined time interval and thereafter to switch the first switching signal into the second state over a second predetermined time interval;
whereine) said measurement circuit is adapted to perform said water intrusion measurement in said second predetermined time interval. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A water monitoring method for a cable including at least one conductor and a screen surrounding said conductor, the method comprising
a1) outputting, from a control unit over a first predetermined time interval, a first switching signal with a first state to a first switching unit in order that first and second sensing wires are connected to a screen potential, the first water sensing wire extending in the screen between the cable beginning and the cable end and the second wire connected to the first water sensing wire at the cable end for forming a loop and extending from the cable end to the cable beginning; - and thereafter
a2) outputting from said control unit over a second predetermined time interval said first switching signal with a second state to said first switching unit in order that said first and second wires are disconnected from said screen potential; and
b) performing water intrusion measurements by a measurement circuit in said second predetermined time interval. - View Dependent Claims (18, 19, 20)
- and thereafter
Specification