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动态应变测量中测试系统受干扰后,出现不同程度的电桥调不平衡、示波图出现干扰波或示波曲线长“毛刺”等现象。排除干扰的方法常用屏蔽法,即将屏蔽电缆的金属屏蔽层接地。但当干扰严重时,光用屏蔽法往往不能完全解决问题。例如,作者在一次现场测试中,由于现场存在极强的电磁干扰源(继电器及测速发电机的火花等),采用各种屏蔽接地措施后干扰仍然严重到使测量无法进行的程度,在这种情况下,最简单的办法是在应变仪与振子之间并联一电容C_B(图1)。电容的大小可根据需要确定,以出现清晰的示波曲线为准。
Dynamic strain measurement in the test system after interference, there are varying degrees of bridge imbalance, oscillogram interference wave or oscillometric curve “glitches” and so on. The method of eliminating interference commonly used shielding method, the shield will be shielded metal shielding. However, when the interference is serious, the light shielding method often can not completely solve the problem. For example, the author in a field test, due to the presence of a strong electromagnetic interference sources (relays and tachometer sparks, etc.), using a variety of shielding grounding interference is still so serious that the measurement can not be carried out in this The easiest way to do this is to connect a capacitor C_B in parallel between the strain gage and the dipole (Figure 1). The size of the capacitor can be determined according to the need to appear clear oscilloscope curve prevail.