When choosing a torquemeter for an application, consider how the measurement signal is output. Analog torquemeters provide +/-10Vdc or +/-5Vdc, while digital torquemeters send a 14-bit signal. Some equipment, however — especially carrier amplifiers — requires an mV/V analog output. When that's the case, you need a low-range torquemeter.
Torque Measurement Basics
Our torquemeters measure torsion with strain gauges embedded in the shaft. A strain gauge is a thin strand of wire where electrical resistance varies slightly with compression and extension. In a quality torquemeter, four are coupled in a Wheatstone bridge configuration. By applying a small excitation voltage, it's possible to measure torque in a shaft while excluding the effects of bending.
Torque in a shaft is static or dynamic. Static torque is twisting without rotation. Dynamic torque occurs when the shaft rotates. S. Himmelstein and Company torquemeters are available for both static and dynamic torque. In case of any doubt as to which is required, contact us for advice.
Torque Output Signals
The Wheatstone bridge arrangement yields a very small voltage. In most torquemeters, a signal conditioner provides amplification to create an analogue output. Digital torquemeters also have a 14-bit output. The low-range torque transducer is designed for users who will provide separate, external amplification, typically through a carrier amplifier.
A carrier amplifier works by converting a very small dc input (for example, the output from the low-range torque sensor) to ac. This is then amplified before being rectified and output as dc. The advantages are absence of any dc drift and high levels of immunity to electrical noise, such as that produced by power lines.
Torque measurement via carrier amplifier is generally seen in older equipment, but excellent noise immunity means there’s still a case for using low-range torque sensors in specialized test and measurement applications. Industries using mV/V analog torquemeters include those building specialized test equipment as well as laboratories needing high confidence in the precision of their measurements. Medical devices along with space and aerospace manufacturing and precision metrology are all application fields.
Choosing a Low-Range Torque Sensor
S. Himmelstein and Company’s mV/V low-range torque sensors are available in flanged and shaft configurations. (Flanged and shaft-style sensors are produced with 400% overload ratings. Only flanged low-range torque sensors are available with 200% overload capability.)
All low-range torquemeters are hardened against EMI as generated by variable speed drives and have excellent immunity to magnetic fields. They offer bidirectional operation and two levels of precision. Code N models have a combined error of under 0.1% while the high-precision Code C models provide better than 0.05%.
Our low-range torque sensors operate on a supply of 6V rms and, as the name implies, provide an output of 1.5mV/V.
Torque Measurement Specialists
Since 1960, we've specialized in building robust, high-precision torque measurement systems. Our in-house machine shop gives us complete control over the manufacture of critical components, and we maintain a calibration laboratory certified to ISO 17025.
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