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冲击、振动对继电器的影响

2013/11/18 12:27:11点击:
机械振动----继电器在强动力设备周围、在运输途中都会遇到一定频率范围、加速度值的振动;随机振动可代表导弹、高推力喷气机和火箭发动机产生的现场振动应力作用。

  (1) 振动对继电器的影响表现在:

  a.振动可能致使机械结构件松动、疲劳、断裂失效;

  b.闭合触点因振动产生大于标准规定时间(10us、100us)的瞬间断开而失效; 断开触点因振动产生大于标准规定时间(10us、100us)的瞬间闭合而失效;

  c.导致活动零件之间的相对运动,产生噪声、磨损和其他物理失效。

  (2) 振动分级: 振动频率范围推荐选用: 10~55HZ; 10~100HZ;10~150HZ; 10~500HZ; 10~2000HZ。 10~5000HZ; 55~500HZ;55~2000HZ;55~5000HZ;100~2000HZ。 振幅(双振幅),加速度推荐选用: 交界频率(57HZ)以下选用双振幅(mm):0.035;0.075;0.15;0.35;0.75;1.0;1.5;2.0;3.5。 交界频率以上,选用加速度(m/s2):4.9(0.5g); 9.8(1.0g); 19.6(2.0g); 49.0(5g);98(10g); 147(15g); 196(20g); 294(30g); 490(50g)

  冲击----继电器在运输、搬运、使用中经常会受到机械冲击的作用。冲击对继电器的影响表现在:

  1)由于冲击,造成结构松动、损伤、断裂而丧失工作能力。

  2)由于冲击,闭合触点产生大于规定要求(10us或100us)的瞬间断开而失效;断开触点产生大于规定要求(10us或100us)的瞬间闭合而失效。

  针对1)要求继电器应具有抗冲击强度的性能,在试验前后进行的规定项目的测量结果,应符合产品标准要求。

  针对2)继电器应具有抗冲击稳定性的性能,要对触点的接触状态进行动态监测。冲击加速度分级(m/s2):147(11ms)、294(18ms)、490(11ms)、 490(3ms)、980(11ms)、980(6ms)、1960(6ms)、1960(3ms)。

  失效率要求

  有些应用场合,对继电器工作的可靠性要求很高,如卫星、火箭、导弹、飞机及程控交换机上用的继电器,失效率等级要求达L级(1×10-6)、Q级(1×10-7); 现将失效指标介绍如下:

  对应美军标失效率等级

  失效率等级符号

  失效率等级名称

  最大允许失效率 λmax 1/10 次

  LMP

  YW WLQ

  Ⅴ级  Ⅴ级  Ⅵ级  Ⅶ级

  3×10 -5 1×10 -5 1×10 -6 1×10 -7

  有失效率要求的继电器,其成本将大幅度上升。用户提出此失效率要求,要非常慎重。