Description
The LZMB is a modular universal force measuring cell with a built-in safety measuring amplifier for SIL3 (IEC 61508, EN 62061) and PL e, category 3 (EN 13849-1). One bridge signal is fed to two galvanically isolated 4 … 20 mA current outputs so that a safety controller can check both channels against each other. A 24 VDC test input raises channel B by 1 mA.
The rated loads are 500, 1000, 1500 and 3000 kg (5 to 30 kN), for compression, tension or tension and compression. The nominal working range is 8 … 16 mA within the valid range of 4 … 20 mA; zero is at 8 mA (compression or tension) or 12 mA (tension and compression), the load resistance max. 500 Ω. Linearity and hysteresis of the measuring cell are 0.5 % of range each, repeatability is 0.05 %, creep and temperature drift are 0.05 % each (per 10 min and per 10 K). The safe overload is 150 %, the breaking load 200 % of range.
The cell is supplied with 24 VDC ±10 % at max. 100 mA. It is connected via two M12x1 connectors: 4-pin for output A and test pulse, 8-pin for output B and supply. Both connection cables are included in delivery. EMC according to EN 61326-1, EN 61326-2-1 and EN 61326-3-1.
Important regarding the safety rating: The TÜV test certificate SIL3 / PL e covers the electronics, not the force measuring cell – according to the manufacturer, the integrated sensor was not part of the tests. Both analogue signals must be evaluated by a controller approved for SIL3 / PL e; it is not included in delivery. A measuring accuracy of the amplifier is not documented.
The material is stainless steel or nickel-plated tool steel, the protection class is IP54, and the electronics are fully potted. Mounting is via rod ends, which are included in delivery, or without rod ends using the threaded bores of the cell. The weight is approx. 343 g (500 and 1000 kg) or 423 g (1500 and 3000 kg), each without rod end and without covers. Operating temperature -25 … +60 °C, storage temperature -25 … +85 °C, humidity up to 96 % RH without condensation.
Advantages at a glance
- Built-in safety measuring amplifier SIL3 / PL e, category 3
- Two galvanically isolated 4 … 20 mA outputs
- 24 VDC test input for diagnostics
- Rated loads 500, 1000, 1500 and 3000 kg (5 to 30 kN)
- Stainless steel, potted electronics, protection class IP54
- Both M12 connection cables and rod ends included