Operation of RU Busbars and Isolators
Operation of RU tires. The main task of the operation of RU tires is to monitor their condition and heating.
When operating the busbars, special attention is paid to the bolted contact connections of the RU busbars with each other and with the terminals of the devices. These connections must meet the following basic requirements:
- the current density in the contact connection of the busbars should not exceed 0.3 A / mm2 for copper, 0.16 A / mm2 for aluminum and 0.075 A / mm2 for steel;
- the voltage drop in the contact connection should not exceed by more than 20% the value of the voltage drop for the entire bus section of the same length;
- the contact resistance at a tire temperature of 70 ° C should not exceed by more than 20% the resistance of the entire stud section equal to the length of the contact joint at the same temperature.
Resistance in the bolted contact connection (Rcon) is roughly determined by the expression n
where n — number of bolts; E — bolt tightening force, kg; k — coefficient equal to 1.2 for copper, 10 for aluminum and 75 for steel.
The heating temperature of the tire contact connection under normal conditions and operating currents should not exceed the temperature of the entire bus section at a distance of 1.5-2 m from the connection point. Control heating temperature done by colored indicators, falling pointers or thermal candles.
Checking the heating of contact connections should be done during peak hours. The tightening force of the tire contact connection bolts must ensure the normalized values of transition resistance and contact stability. Bolts are tightened with a special wrench with adjustable force (torque) or a wrench, but using a dynamometer.
When tightening bolts and nuts with ordinary (spanners, adjustable, etc.) spanners, the use of a lever is not allowed. The tightness of the tires in the contact joint is controlled with a probe (10X0.05 mm), which should not enter between the contact surfaces of the tires to a depth of more than 6 mm. Assembled and connecting RU tires must have the phase colors provided by PUE.
Operation of RU insulators... Single-element support and sleeve insulators of RU are periodically subjected to power frequency voltage tests, the values of which are given in the table. 1.
Note. Multi-element insulators are tested by applying a voltage of 50 kVeff at supply frequency to each insulator element for 1 minute.