This safety megohmmeter was developed to carry continuity and isolation measurements on pyrotechnical elements where user safety is at stake.
Two types of conditions define the user safety:
Measurement conditions:
- Measuring current much lower than the current of non-fire
- Connection to the test line only for the activated period of measurement
- Discharge of residual electrical charges
Safety conditions:
- No overshoot of maximum current even in case of instrument failure (electronics breakdown, internal short-circuit…)
- Permanent self-checking of the instrument internal functions before connection to measurement channel
Measurement principle
The principle relies on an internal device of permanent self-calibration which guarantees, over a short and long-term period of time, the high reliability of the measurements carried out by continuously correcting the drifts of gain and offset.
Measurements start with an external input signal. The result of the measurement is internally processed to supply information whether the measured value is within tolerance limits set by the operator.
All parameter settings are entered by keyboard with a locking of the parameters by key. Our units are equipped with dry contact output and S232 connection that allows process automation and implementation of traceability.
On request, our existing products can be adapted to your specific requirements: Adapted protocole RS232, other testing voltage, integration, processing software…
Two switching units (INT 17 and INT 17 HT for high testing voltage) are also available in option to interface the devices under test (initiators, airbags…) with IND pyrotechnical ohmmeters / megohmmeters. The contact switches are usually monitored by shared automation (0 24 V) and earth bounding control (contact or transistor). Automation inputs are protected against any change of polarity.
Megohmmeter function
| Range | 0 MΩ to 100 MΩ |
| Resolution | 0.1 MΩ |
| Accuracy | ± 1% from 0 to 50 MΩ ± 2% from 50 to 100 MΩ |
| Measurement type | 2 wires |
| Measuring current | 10 mA (Further current on request) |
| Test voltage | 45 V (Further voltage on request) |
| Cycle time | < 2 s |
Further features
| Parameter setup | – By keyboard with locking of parameters by key – By serial link |
| Line offset correction | By measurement of line value with validation |
| Triggers | – 24 V at 5 mA – Programmable on opening or closing – Dry contacts in option |
| Output signals | Dry contacts – NO or NC, programmable for: ohmmeter channel and megohmmeter channel measurement, end of cycle |
| Counters | – Counter: Measurement OK – Counter: Measurement out of tolerance – Counter: Measurement out of range – Counter: Measurement total |
General specifications
| Size | 280 x 155 x 290 mm |
| Display | Backlit LCD display, 2 lines with 20 characters each Front panel LED showing: – Flashing green: measurement underway – Fixed green: measurement OK – Fixed red: measurement out of tolerance or out of range |
| Supply | 220 VAC – 50 Hz |
| Communication ports | RS 232 or automation |
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