Strain gauges and transducers are used in various sites of civil engineering and construction for the purpose of safety management during the works and long term management of the structures. The cables of these strain gauges and transducers are often extended in lengths of several tens or hundreds of meters up to a data logger placed in a measurement room or office of the site in order to enable a centralized management. If a vicinity of the strain gauges/transducers or the cables is struck by lightning, a surge current is induced in the cable, even if the strain gauges/transducers or the cables are not directly struck by lightning. The surge current may cause high voltage in the cable, thus causing damages in the strain gauges/transducers and/or data logger.
We offer arresters which are especially designed to protect strain gauges, transducers and data loggers from such high voltage. The arrester NZ-6B is connected to the transducer cable, and the arrester NZR-7B or NZ-7C is connected to the cable between the data logger and the switching box. These arresters work to route a surge current to ground when it occurs, so that the surge current does not cause damage in the transducer or data logger. In addition to the use of arresters, it is also recommended to use an isolation transformer having a small electrostatic capacity for the power supply to a data logger. It can reduce an influence of momentary high voltage in commercial power source which may be caused by lightning.
- Data Logger TDS-540, TDS-630, TDS-530, TDS-303, TDS-602
- Switching Box ASW-30C, ASW-50C, SSW-50D
- TML-NET measuring system NDR-100, NIF-100, TC-35N, MD-111, TDS-150-06
Examples of arrester connections
Ex. 1: Extension between measuring instrument and first-stage switching box (ASW switching box)
Ex. 2: Extension between measuring instrument and switching box, and between each switching box (ASW switching boxes)
Ex. 3: Extension between measuring instrument and switching box (ISW switching box)
Ex. 4: Measures for network system (TML-NET)
These are devices intended for protecting transducers and instruments from the influence of induced lightning. The arrester NZR-7B or NZ-7C is connected to the cable between the data logger and the switching box, and the arrester NZ-6B is connected to the transducer cable. If a surge current is induced in the cable, these arresters work to flow the surge current to ground so that the transducers and instruments are protected from the high voltage.
- NZR-7B Connected between a data logger and a switching box. Isolates between the instruments to prevent induced current flowing into the instruments.
- NZ-7C Connected between a data logger and a switching box. Induced current is grounded.
- NZ-6B Connected between a transducer and a switching box. Induced current is grounded.
- NNZ-2A Connects a network-type measuring system TML-NET, to separate measurement instruments and block induced current
- SAT series These are connecting terminals with surge absorbers to protect transducers and TML-NET devices.