原理：
超声波物位计的工作原理是由换能器（探头）发出高频超声波脉冲遇到被测介质表面被反射回来，部分反射回波被同一换能器接收，转换成电信号。超声波脉冲以声波速度传播，从发射到接收到超声波脉冲所需时间间隔与换能器到被测介质表面的距离成正比。此距离值S与声速C和传输时间T之间的关系可以用公式表示：S=CxT/2。
由于发射的超声波脉冲有一定的宽度，使得距离换能器较近的小段区域内的反射波与发射波重迭，无法识别，不能测量其距离值。这个区域称为测量盲区。盲区的大小与超声波物位计的型号有关。

特点：
由于采用了先进的微处理器和独特的EchoDiscovery回波处理技术，超声波物位计可以应用于各种复杂工况。
“虚假回波学习”功能使得仪表在多个虚假回波的工况下，可正确地确认真实回波，获得准确的测量结果。
换能器内置温度传感器，可实现测量值的温度补偿。
超声波换能器采用最佳声学匹配之专利技术，使其发射功率能更有效地辐射出去，提高信号强度，从而实现准确测量。

应用：          各类工业领域的液位测量，特别是水处理工业。
测量范围：        液体：WTCSL551 [0.25…4m] / WTCSL552[0.4…8m] / WTCSL553[0.5…15m ]
过程连接： WTCSL551 [G1½A] / WTCSL552 [G2A ] / WTCSL553 [ 换能器外壳材料： PTFE、PU/PC
过程温度： -40…70°C
过程压力： -0.2…1bar
信号输出：        两线制/四线制 4…20mA/HART
详细介绍：
许可证
P 标准型(非防爆)
I 本安型(Exia IIB T6)
换能器材料/过程温度/防护等级
A PU/PC/（-40～70）℃/IP66
电子组件
B   (4～20)mA/HART两线制
C   (4～20)mA/(22.8～26.4)V DC/HART两线/四线制
D   (198～242)V AC/HART四线制
外壳／防护等级
A 铝/IP67
B 塑料/IP66
D 铝两腔/IP67
G 不锈钢316L/IP67
电缆进线
M   M20x1.5
N   ½NPT
现场显示/编程
A 带
X 不带
注:本安型只可选“A”型外壳，及“C”电子组件;“C”或“D”电子组件只能配“D”外壳。

Principle: The principle of ultrasonic level meter is that the transducer (probe) sends out high frequency ultrasonic pulse when the surface of the measured medium is reflected back, and part of the reflected echo is received by the same transducer and converted into electrical signal. the ultrasonic pulse propagates at acoustic velocity, and the time interval required from transmitting to receiving the ultrasonic pulse is proportional to the distance from the transducer to the surface of the measured medium. The relationship between the distance value S and the sound velocity C and transmission time T can be expressed by formula: S=CxT/2.. Because the transmitted ultrasonic pulse has a certain width, the reflected wave in the small section area close to the transducer overlaps with the emission wave, which can not be recognized and its distance value can not be measured. This area is called the measurement blind area. The size of blind area is related to the model of ultrasonic level meter. Features: Because of the advanced microprocessor and unique EchoDiscovery echo processing technology, ultrasonic level meter can be used in various complex working conditions. The function of "false echo learning" enables the instrument to correctly confirm the true echo and obtain accurate measurement results under the condition of multiple false echoes. transducer built-in temperature sensor, which can realize the temperature compensation of the measured value. The ultrasonic transducer adopts the patent technology of best acoustic matching, so that its transmitting power can radiate out more effectively and increase the signal intensity, so as to realize accurate measurement. Applications: liquid level measurement in various industrial fields, especially the water treatment industry. Scope of measurement: Liquid: WTCSL551[0.25…4m]/WTCSL552[0.4…8m]/WTCSL553[0.5…15m] Process connection: WTCSL551[G1½A]/WTCSL552[G2A ]/WTCSL553[ flange or hanger] Transducer housing material: PTFE、PU/PC Process temperature: -40.70°C Process pressure: -0.2...1 bar Signal output: Double wire / four wire 4.20 mA/HART Details: Licences P standard (non-explosive) I intrinsically safe (Exia IIB T6) transducer material/process temperature/protection level A PU/PC/(-40~70)℃/ IP66 Electronic components B (4~20) mA/HART two-wire system C (4~20) mA/(22.8C (4~26.4) V DC/HART two-wire/four-wire system D (198~242) V AC/HART four-wire system Shell/protection level A aluminium/ IP67 B plastics/ IP66 D aluminium two cavities/ IP67 G stainless steel 316 L/IP67 Cable feed line M M20x1.5 N ½NPT Field display/programming A belt X not Note: This safety type is optional only for "A" type enclosure, and" C" electronic assembly ;" C" or "D" electronic assembly can only be fitted with" D" enclosure.