一、概述Summary

　　固态继电器(Solid State Relay)简称为SSR。它是一种全部由固体电子元器件组成的新型的无触点开关器件，它利用电子元器件中的大功率三极管、功率场效应管、单向可控硅和双向可控硅及模块等器件的开关特性，可达到无触点、无火花的接通和断开电器电路。它又称为无触点开关。SSR 一般为四端有源器件，其中两个控制端和两个输出端。输入、输出端可靠隔离。当输入端加控制信号时，输出端就进行开或关转换。

　　The solid state relay is usually called SSR for short. It is a new type of non-contact switching device completely composing of solid electronic elements, it adopts the switching characteristics of high power audion, power field effect tube, one-way and two-way controllable silicon and module to make and break the circuit without contact or spark. It is also called non-contact switch. SSR is usually a four- terminal active device including two control terminals, input and output terminals, and input and output terminals own reliable isolation. When control signal is connected with input terminal, the output terminal will switch over for on or off.

二、固态继电器的特点 Character of Solid State Relay

    固态继电器具有高可靠性：SSR内部没有任何的机械部件，结构上采用灌封全闭式结构。因此，SSR具有耐振、耐潮、耐腐蚀、长寿命和工作可靠的特点。固态继电器具有低噪音：交流型SSR都采用了过零触发技术，因此在线路中能有效的降低dv/dt和di/dt，固态继电器具有开关速度快：SSR的开关速度比机械开关快的多，直流固态继电器的导通和关断时间可达到几十微秒。SSR能与TTL、CMOS等逻辑电路兼容的优点。
    The solid state relay owns high reliability: there isn't any mechanical part inside SSR, and it uses totally-enclosed encapsulation　structure. Therefore, SSR owns characteristics of resistance to shock, moisture resistance, corrosion resistance, long service life　and reliable operation. SSR owns Iow level of noise: each AC SSR adopts zero-crossing triggering technology, so that it could reduce　dv/dt and di/dt effectively in the circuit. SSR owns fast switching speed: The switching speed of SSR is much faster than the one of　mechanical switching with a making and breaking time reaching tens of microseconds for DC solid state relay. SSR could be compatible
with logic circuit like TTL, CMOS, etc.

三、固态继电器的使用 Usage of Solid State Relay

    固态继电器使用中出现的大部分问题是将特殊的负载加在固态继电器上而引起的。因此，在使用固态继电器以前，首先应了解一下特殊形式的负载给固态继电器的可靠工作造成的影响。
    Most problems arising during the using of SSR are caused by special load on solid state relay. Therefore, people should first learn of　the effect to reliable work of ssr caused by special load before use.

▲阻性负载：SSR中最简单的应用场合是恒定的电阻性负载。只要电路稳态电流的额定值和开断电压在SSR的允许范围之内，继电器就能可靠的工作。
▲Resistive Load: The simplest application for SSR is invariable resistive load. As long as the rated steady-state current and breaking voltage of the circuit are within the allowable range of SSR, the relay could work reliably.

▲灯负载：白炽灯负载，虽然基本上属于阻性负载，但也存在一些特殊的问题。这是因为冷钨丝的电阻大约是热钨丝的电阻的1/10，所以会出现很
大的启动电流。所以，必须把启动电流限定在固态继电器所规定能承受的范围内。
▲Lamp load: incandescent lamp, which is although basically belong to resistive load, also has some special problems. This is ecause
that the resistance of cold tungsten filament is about 1/10 of the one of hot tungsten filament, there will be a very high start current. Therefore, the start current must be limited within the endurable range stipulated by solid state relay.

▲容性负载：容性负载虽然不太普通，但在应用中也会遇到。对于低阻抗容性负载必须谨慎，要确保不超过SSR的di/dt。如果没有外加限制阻抗， 充电时容性负载di/dt的可以按近无穷大，采用零电压导通的SSR限制容性负载di/dt值是特别有用的方法。在使用SSR时，要注意SSR的最大阻断电压的安全范围．在接近峰值线电压处放电时会产生一个大的破坏性的di/dt值，容易使负载导通，因此对容性负载的瞬态电压必须加于限。 对于大的容性负载，串联线路阻抗把di/dt限制在规定值内是非常必要的。它能保护SSR承受偶然的又不是不可避免的非常大的瞬间电压。
▲Capacitive Load: Although the capacitive load is not so common, it is applied sometimes. Take particular care for capacitive load of
low impedance, and don't exceed di/dt of SSR. If there is no extra limiting impedance, capacitive load di/dt could reach near infinite
during charging, it is a very useful way to limit capacitive load di/dt by zero-voltage conduction. Pay attention to the safety range of
maximum blocking voltage during SSR using, it will result in a quite destructive di/dt value when it discharges near peak line voltage,
which will easily make the load conduction, so transient voltage of capacitive load must be limited. For large capacitive load, it is
very necessary to limit the di/dt within the stipulated value by series circuit impedance, which can protect the SSR suffering
accidental and unavoidable high transient voltage.

▲感性负载：虽然交流SSR在零电流时进行切断，但能产生其它现象而出现的问题。在电流为零的一瞬间，SSR“换向”(颠倒电流方向)SSR在换 向的瞬间是不导电，所有的瞬态线电压跨接在它的接线端上，产生了一个大的dv/dt(电压变化速率)，该“换向”dv/dt能立即导通固态继电器， 从而使SSR不释放而出现“锁住”状态。交流固态继电器基本上都加有RC以增加其抗dv/dt的能力，直流感性负载在开时会产生很高的反电势，通过在负载两端加续流二极管，直流固态继电器就能可靠控制感性负载。
▲Inductive Load: Although AC SSR is cut off during zero current, there is still problem due to other phenomenon. On the moment of zero current, SSR will "change over" (reverse current direction), SSR doesn't make conduction on the moment of reverse, and all of the transient line voltage is bridged over on the connection terminal, which produces a high dv/dt (voltage variation velocity) capable to make the SSR conduction immediately and "lock up" state appear without release. Most AC solid state relay has RC for enhance of resistance performance to dv/dt, there will be very high counter-electromotive force when DC inductive load is open, and the DC SSR can control inductive load reliably by adding freewheeling diode in the two terminals of the load.

▲马达负载：马达在启动时，马达往往有很大的启动电流，而断开时会产生很高的电压。对于大的启动力矩或惯性并与机械负载连接的马达电流应慎重的确定，以保证其在固态继电器的浪涌限额之内。马达可能在短时间内反复启动，因此必须考虑多启动电流SSR热工作点上的影响。还有，应考虑出现异常的转子失速的可能性。此时马达的启动电流远大于正常值。对于长时间的失速状态，应选用安全系数很大的SSR或用保险丝保护。某些马达线路产生的反电动势要求SSR具有一个较高的阻断电压，否则马达可能出现“锁住”或不规则关断现象。
▲Inductive Load: Although AC SSR is cut off during zero current, there is still problem due to other phenomenon. On the moment of zero current, SSR will "change over" (reverse current direction), SSR doesn't make conduction on the moment of reverse, and all of the transient line voltage is bridged over on the connection terminal, which produces a high dv/dt (voltage variation velocity) capable to make the SSR conduction immediately and "lock up" state appear without release. Most AC solid state relay has RC for enhance of resistance performance to dv/dt, there will be very high counter-electromotive force when DC inductive load is open, and the DC SSR can control inductive load reliably by adding freewheeling diode in the two terminals of the load.

▲变压器负载：SSR控制变压器的初级负载时，应检查次级负载的特性。这是因为次级负载又可以作为SSR有效负载一部分，同样次级负载线路上的瞬态电压被转换并加到SSR上。根据变压器在断开时的磁通情况，它可能会出现一个特殊的问题，即是变压器可能在连续施加电压的第一个半周期内饱和，这种饮和现象可能把一个非常大的电流(为额定初级电流的10—100倍)加到SSR上，超过其半周期浪涌值。在这种情况下，与零电压导通的SSR相比，随机导通SSR具有较强的生命力。因为它们通常要求变压器只承受第一个半周期电压的一部分，相反，零电压导通SSR通常是在零电压点(半周的起点)闭合，因此SSR必须承受最恶劣条件即饱和电流。变压器饱和电流的严重程度有很大的差异，主要取决于变压器的磁性材料，饱和的初级阻抗，线路阻抗等。
▲Transformer Load: When SSR is used to control primary load of transformer, the characteristic of secondary load should be examined, as the primary load can be made as one part of effective load of SSR, meanwhile, the transient voltage of secondary load circuit is transferred and applied to SSR. According to magnetic flux condition during transformer breaking, there may be a special problem, namely, the transformer may be saturated in the first half cycle of consecutive voltage application, this saturation phenomenon may cause a very high current (10--100times of rated primary current) applied on SSR, which exceeds the surging value of half cycle. In such condition, compared to zero-voltage conduction SSR, random conduction SSR has stronger life force, as it generally requires that the transformer should only bear one part of first half cycle voltage, by contraries, zero-voltage conduction SSR usually closes in zero-voltage point (starting point of half cycle), so that the SSR must endure the worst condition, namely, saturated current. There is a big difference of severity degree for transformer's saturated current, and it is mainly subject to magnetic material of transformer, saturated primary impedance, circuit impedance, etc.

四、固态继电器的基本特性 Basic Character of Solid State Relay

• ▲输入信号能与计算机终端及数字逻辑电路兼容。
  ▲输入回路与输出回路之间光隔离，隔离耐压4000V
  ▲分过零触发和随机触发两种规格。
  ▲发光二极管指示工作状态。
  ▲内置阻容吸收回路。
  ▲介质耐压强度：>2KV
  ▲介质绝缘强度：>50MΩ
  ▲动作应作时间：ON>10ms/OFF<10ms
  ▲工作环境：-20℃-+70℃
• ▲Input signal could make computer terminal and digital logic circuit compatible.
  ▲Optical isolation between input and output circuit, with isolating withstand Voltage of 4000V.
  ▲Two specifications: zero-crossing triggering and random triggering.
  ▲LED indication for working condition.
  ▲Built-in resistance-capacitance absorption circuit.
  ▲Dielectric withstanding voltage: >2KV
  ▲Dielectric insulating strengh:>50MΩ
  ▲Actuation time:ON>l 0ms/OF F< 10ms
  ▲Working environment:- 20℃-+70℃
  

五、固态继电器的应用 Application

　　
　　SSR系列固态继电器采用阻燃工程塑料外壳，环氧树脂灌封，螺纹引出端子接线，具有结构强度高，耐冲击，抗震动性强，输入端驱动电流小，可方便与计算机终端和数字控制电路接口，广泛应用于石油化工仪器设备、制药机械、食品机械、包装机械、纺织机械、塑料机械、数控机床、娱乐设施等自动化控制领域。
特别适用于腐蚀，潮湿防尘，要求防爆等恶劣环境，及频繁开关的场合。
　　 SSR series solid state relay adopts flame resistant engineering plastic case, epoxy resin encapsulation, screw thread educing terminal　connection with high-strength structure, impulse resistance, high shock resistance performance, small driving current for input terminal and convenient connection with computer terminal and digital control circuit, the product is widely used in automatization control fields such as petroleum, chemica industry, instrument and meter, pharmacy machine, food machine, packaging machine,textile machine, plastic machine, numerical control lathe, entertainment facility, etc., especially for severe environment full of corrosion and moisture or requiring explosion-proofand dust resistance or places demanding frequent switching.

六、固态继电器使用注意事项 Operation Notice

▲电阻性负载不能超过额定电流的60%。
▲电感性或容性负载不能超过额定电流的40%。
▲电机负载不能超过额定电流的20%。
▲固态继电器要配用适合其工作需要的散热器，负载散热条件较差时应适当放宽余量。切忌负载短路。
▲过流保护措施：过流和负载短路是造成SSR内部输出可控硅永久性损坏的主要原因，快速熔断器和空气开关是过流保护方法之一，小容量也可选用保险丝。
▲过压保护措施：过压保护可以采取并联压敏电阻(MOV)，MOV面积大小决定吸收功率，MOV的厚度决定保护电压值，一般220V系列SSR可选取 471/10D压敏电阻，380V系列SSR可选取681/10D压敏电阻，480V系列SSR的可选取821/10D压敏电阻。

▲Resistive load could not exceed 60% of rated current.
▲Inductive or capacitive load could not exceed 40% of rated current.
▲Electric machine load could not exceed 20% of rated current.
▲Proper radiator adapted to the working requirement of solid state relay should be equipped, the allowance should be widened when the load radiating condition is not so good. Short-circuit load is not allowable.
▲Over Current Protection: over current and short circuit are the main reasons for permanent damage of output controllable silicon in the SSR, and using fast fuse and air switch is one of the methods for over current protection, fuse is also available for small capacity.
▲Over Voltage Protection: It could adopt parallel voltage-dependent resistance(MOV), the MOV area decides the absorption power, while its thickness decides the protective voltage value, generally, 471/1 OD voltage-dependent resistance for 220V series SSR, 681/1 OD voltage-dependent resistance for 380V series SSR, 821/10D voltage-dependent resistance for 480V series SSR.

七、固态继电器的命名 Denomination of Solid State Relay