Like the same number of outlet switch, the number two switch is divided into three phases of ABC and three sub-switches. In more than ten minutes, the power plant maintenance personnel were busy and connected to various routes.
The test went on very quickly. During this period, the operator shook it with a few shaking times, and the pointer stabilized at about 2,700.

Then the conclusion was quickly concluded that the operators in Fengzhou were not allowed to announce this conclusion: "2700mΩ, within the allowable limit, the insulation resistance performed well."

He said, then turned his head and looked at the microampmeter: "9μa, below the standard value, does not count as leakage."

In short, this switch performed normally and even excellently in this insulation test.

After waiting for a long time, the final result was that two sentences were coldly suppressed, without a glimmer of hope for recovery, which made Miao Delin almost unable to stand firm.

He turned to Nangang and begged: "Director Nan, can you try a few other switches? Even if there is a problem with the equipment, it is impossible for each switch to be exposed."

"What a joke? It's safely running now. Is there time to stop the line in turn and let you play house?" Nan Gang said with a face, "Isn't this over yet? There is also an insulating oil test."

When Miao Delin heard this, his heart was already at the bottom of the valley.

At this time, Ou Wei comforted him: "Old Miao, don't be anxious. Insulation oil is the big one. As long as water enters, it will eventually seep into the oil."

"Yes...yes..." Miao Delin had no choice but to nod his head and ordered his subordinates to start oil drainage testing.

Zhang Yifu looked at the speed of oil discharge, then looked at the bulky detection instrument. It took half an hour to finish it, and then he didn't want to look at it anymore. He believed that people in Fengzhou had measured the temperature. Generally speaking, there was no problem with the temperature, and there would be no problems with short circuit and leakage. After the test was completed, 80% Miao Delin had nothing to say, so he could only lower his head and be criticized.

With such a disheveled mood, he left the team again. He returned to the explosion scene of the No. 1 qualifier switch with his hands behind his back. There was no one here now, so it was a time to take a closer look.

Zhang Yifu also called out the specific structure of the circuit breaker for a low-oil circuit breaker. According to the latest version of the paper of the Academy of Electrical Sciences, he added a few reasons for the explosion. From the perspective of the cause, there was no big progress in later generations. It was impossible to get water inlet and installation errors.

From the scene, all the supporting porcelain sleeves of the b-phase switch were blown up, and the insulated pull rod was broken into four sections. The fuel tank turned over to the ground, and three of the four anchor screws of the b-phase current transformer were broken. The conductive rod in the arc extinguishing room at the outlet was broken and inclined to the air. One side of the knife gate was pulled up from the bracket, which was a terrible sight.

Under the impact of the explosion, the two switches of phase a and c were tilted around, and the fragments that exploded even flew dozens of meters away, and no one dared to move so far.

Zhang Yifu first focused his attention on the relatively complete A and C phase switches. One of these two was turned down and the other porcelain bottle was still standing. Most people did not focus on this, but mainly observed the b phase wreckage of the explosion. At this moment, Zhang Yifu was still idle and studied the two relatively complete switches.

He leaned closer to observe, and after a night of rain, the inside was already full of water.

If there is no damn rain, just dissect these two switches and study them. But in the current situation, the rain has already entered, and there is no meaning of analysis.

Zhang Yifu wanted to find out the inside through the broken mouth of the porcelain bottle to see if there were any clues, but the inside was always dark and the visibility was very low. He wanted to open it but it was difficult to disassemble it by himself. After all, this was the scene of the accident. Before the leader ordered it and before the professionals came, they could not be touched.

So he had to look at the wreckage again.

Hope the corpse can speak.

When you pick up two or three pieces of porcelain bottle, it is just fragments, with traces of burning and deformation, but it is normal.

The inside of the broken fuel tank is full of water. Judging from the explosion, it should have happened at the upper part of the fuel tank. Remember this first.

So, Zhang Yifu squatted down slowly again, staring at the pull rods and equipment inside and observed.

Even at this moment, the switch is still in the closing position. Looking at the arc extinguishing room, the most likely place to explode, is relatively complete, and the contacts mentioned by everyone have not yet turned into residue. If the explosion happened here, they would at least break and fly away.

If it is really an installation error during maintenance, the explosion should have occurred in these places, and there shouldn't be a complete corpse.

After looking around, the seemingly miserable accident scene was not as fragmented as imagined, and many key components were still there. As for the things that flew the farthest, they were not the things inside, but the pieces of porcelain bottles wrapped outside.

Logically speaking, the specific point where the explosion occurred should be the most severely damaged place, so Zhang Yifu lowered his head and began to look for the one who exploded the worst.

After searching for a while, he found that two of them were miserable and were incomparable.

One is the branch on the left side of the character "v", which is the erected porcelain bottle, which is basically gone.

The other is a flat metal rod that broke everywhere. After comparing it with the design drawing in your mind for a few rounds, Zhang Yifu could confirm that this thing is called an insulating pull rod.

Simply put, an insulated pull rod is the rod that pulls the contacts at both ends of the line and touches each other or separates.

Just like the electric flowers that burst out when plugging and unplugging the pin at home, when the two ends of the line are not connected or the wire is broken, an overvoltage will also be generated. A terrible arc is originally played with high voltage electricity, and the voltage and current at this moment are naturally even more terrifying. This requires pulling the insulating rods at both ends to be strong enough to avoid being broken down by voltage, which will affect other parts inside and outside the switch.

This pull rod must not only be hard enough and strong enough, but also be insulated enough.

Unfortunately, the long insulating lever that should have been broken into four sections, splitting everywhere.

The arc extinguishing chamber that has the largest voltage strength is not that bad, so why is this pole that should be very hard is so bad?

Even though he was curious, Zhang Yifu did not dare to move around. He could only squat in front of those four sections and observe them one by one, thinking hard like a child watching an ant moving, and reappearing the true appearance of the pull rod in his mind.

As I was studying, a damn voice broke my mind.

"The second line switch has tested two phases, and the last phase is left." Xia Xue walked over with a smile and saw Zhang Yifu thinking hard, "Oh, has the big experts in the whole system started working?"

"Go and go, don't make trouble, I'm thinking about things here." Zhang Yifu waved his hand impatiently.

Xia Xue was obedient, but she was not Xia Xue. She squatted side by side with Zhang Yifu without caring about anything and looked at the pitiful lever.

So one child became two children.

After a brief observation, Xia Xue pointed at La to catch a deformed and raised place and said, "What is this?"

"I'm thinking."

"And here." Xia Xue pointed to the bottom again, "What is this black line?"

"What black line?" Zhang Yifu stared at the place where Xia Xue pointed and studied it, "Hey! It seems there is a black line."

The two of them looked closely and saw that although the black line was not horizontal and vertical, it was quite regular at the bottom of the pull rod. At rough estimates, the width was about 5 mm.

"Is this normal?" Zhang Yifu asked. This knowledge is too detailed and difficult to find. He really has no time to move it out. It seems that he is too arrogant if he claims to be the whole field.

"It should be abnormal." Xia Xue muttered, "I have seen it in a journal. Such traces should be caused by burning."

"Burning? Blackened?"

"Yes, I can't be sure, I saw it in technical journals."

I have to say that real talent and knowledge are solid. Remembering the human brain and remembering the computer are still different.

Following Xia Xue's thoughts, Zhang Yifu muttered: "Suppose you are right, there has been a burn here... But why is it only here? This is so small..."

"It's oily." Xia Xue's expression moved and she immediately said, "The pull rod is penetrated into the oily surface. This part should be the contact part with the oily surface, the oily surface line!"

"Wait, you mean, the oil burns first? Then it explodes?"

"I can't be sure, but this is what the black line should mean." Xia Xue nodded and fell into deep thought. "If other parts explode first, the fuel tank will overturn and oil will splash everywhere, and there will be no chance to generate this black line... According to this logic, the oil surface part will burn first and explode later."

"That's right." Zhang Yifu shook his head immediately, "Insulation oil cannot burn, no matter how high the temperature is, otherwise the switch will explode every day."

"How do you explain this black line? At least it's high temperature, at least there is flashing, right?"

Flashover, simply put, is a direct manifestation of the destructive discharge caused by the insulator surface and the insulation problem.

"Flashing...I remembered it!" Zhang Yifu suddenly pointed to the occasional bulge on the pull rod, "The place you just mentioned is a bubble phenomenon, which only happens in the flashing."

"So that's to say, can you be sure that a flashover has occurred?"

"Yes, there is a flashover on this insulating rod. It is not a problem inside the insulator. If the internal conduction is broken down and there will be no bubbles. There is no problem with this insulating rod itself..." Zhang Yifu felt that Xia Xue had opened a door for him, but he still didn't catch something in the door, and he was still a little bit away.

Xia Xue also felt the same way.

"If the flashover is... the surface of the insulating rod is high in temperature and high pressure, and the marks of blackening are generated at the oil surface... But liquid insulating oil will not burn... No matter how high the temperature will not burn, no matter how high it is..."

As they were talking, the two of them widened their eyes at the same time, and a "bang" sounded in their heads.
Chapter completed!