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Technical characteristics analysis of static current voltage time relay

Wang Xiaodan Hunan substation repair and installation company (Hunan Changsha 410002) Wang Yu Changsha Electric Power School (Hunan Changsha 410131)

0 introduction

with the development of science and technology in China, analog electronic technology and digital electronic technology have been widely used in relay protection and automation equipment of power system, Electric relay protection and automation devices have gradually transitioned from conventional electromagnetic protection to digital protection. As a basic part of relay protection devices, relays have gradually developed from electromagnetic protection to static protection. Although the electromagnetic relay has played a positive role in the safe and stable operation of electricity in the past few decades, it is undeniable that the incorrect action of the device caused by the large discreteness of its action value and the easy jamming of the mechanical part has brought harm to the system due to the structural use of electromagnetic and mechanical principles. In order to solve this problem in the principle and structure of electromagnetic relay, many domestic manufacturers have developed a relay based on digital electronic principle, which is called static relay. Due to the superior performance of the principle and structure of the static relay, it is gradually replacing the electromagnetic relay developed in the early stage

1 analysis of technical characteristics of several main static relays

1.1 static current (voltage) relay

1.1.1 application

static current and voltage relay is divided into static overcurrent relay, static overvoltage relay and static low voltage relay. Overcurrent relay is mainly used for overcurrent and overload protection of power lines and power equipment, as well as current disconnection locking element and current starting element. Overvoltage relay is mainly used to distinguish the overvoltage of lines and power equipment, and is used as overvoltage protection. The low-voltage relay is mainly used to distinguish the wear-resistant testing machine of lines and power equipment. The specific use method is voltage reduction, which is used as power loss protection or combined with current relay to form a composite voltage lockout overcurrent protection

1.1.2 working principle

as shown in Figure 1, the main component of the current voltage relay is the integrated operational amplifier, which has an open-loop amplification of more than 10000 times and a very small offset voltage and current, and is the best component to form an analog relay protection. The AC voltage or current is transformed into the AC voltage required by the relay through the AC converter, and then the harmonics beyond 50 Hz are filtered through the 50 Hz band-pass, and then transformed into DC voltage through rectification and filtering, and sent to the setting circuit, which changes the setting value by changing the amplification factor of the operational amplifier. The output voltage UZ of the setting circuit is sent to the level detector to compare with the comparison voltage UB, and then acts on the outlet relay J through driving

for overcurrent or overvoltage relay, under normal conditions, when uz < UB, relay J does not act; In case of fault, when uz > UB, relay J acts

for low-voltage relay, under normal conditions, UZ> UB, relay J does not act; In case of fault, when uz < UB, relay J acts

1.1.3 main performance and characteristics

static relay has advanced principle, stable performance, high insulation level and reliability. Compared with the electromagnetic relay, which actively promotes the exchange of ceramic aluminum new materials in the fields of automotive lightweight, aerospace and military industry, it has the advantages of high accuracy of action value, small discrete value, wide setting range, fast action and return, high return coefficient, high transformer burden and cooling speed, and low DC power consumption. At the same time, the setting value of Ji · 44 · electric appliance is easy to set and the debugging is simple, especially because the "new materials" of its shell and outgoing line refer to the newly developed or under development materials with superior performance, which are completely the same as the electromagnetic relay, which is convenient for the renewal of the electromagnetic relay

1.2 static time relay

1.2.1 application

static time relay is mainly used as the time delay element of relay protection in power plants and substations. At the same time, it is also suitable for other industrial fields that need precise time delay control. It is suitable for updating the electromagnetic relay to solve the urgent contradiction of difficult coordination of protection time differential caused by the use of electromagnetic time relay in current power system relay protection. At present, there are many types of static time relays produced in China, and they have various time periods from 2 ms to 10000 s, so that users can choose different time requirements. Since the static time relay has its superior performance, it has been widely used in the power system of our province since the early 1990s

1.2.2 working principle

as shown in the figure, the static time relay logic circuit is composed of IC modules, using crystal oscillator frequency division, and programmable subtraction counting to achieve delay. When the external starting quantity is converted into weak current signal through the instantaneous circuit, it is sent to the control logic. The control logic is sent out in 3 ways: 1 way to the frequency divider, start the timer and start timing; If the other two routes are sent to outlet 1 and outlet 2 respectively, open its outlet circuit. When the time TQD of external starting quantity is greater than the setting time t1zd, outlet 1 acts and T1 light is on at the same time. When the external start-up time TQD> t2zd setting time, outlet 2 acts and T2 light is on at the same time. In order to overcome the action time error caused by the inherent action time of the outlet relay, a compensation circuit is set in the relay, which greatly reduces the error between the setting time and the actual action time

1.2.3 main performance and characteristics

static time relay is composed of imported integrated circuit chips and components, with advanced principle, stable performance and high reliability. Compared with electromagnetic time relay, it has the advantages of high accuracy of action value, small differential, convenient setting, wide delay range, low DC power consumption and so on. Especially, because its shell and outgoing line are exactly the same as the electromagnetic relay, it is convenient for the renewal of the electromagnetic relay

2 practical application and development trend of static relay

the development process of relay in China has gone through three generations. The first generation is from the early 1950s to the mid 1970s. Induction relays are widely used in electrical relay protection, which are characterized by complex structure, huge volume and stable action

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