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- The SA380TX can monitor 1 x Bender type IRDH265 / 365 insulation monitor.
- In addition to the isometer, volt-free contact outputs from Bender fault-repeater devices (such as the ESD-470) may also be connected the SA380TX general purpose digital inputs.
- If a 4-20mA output converters such as the RK170 is utilised, this can be connected to the SA380TX general purpose analogue inputs, although RS485 connection is preferred.
- Other models of Bender isometer may be supported over RS485 - check the Bender documentation to see if the RS485 protocol matches
- Please be aware that 1 x SA380TX can only monitor 1 x Bender Isometer. This is a limitation of the Bender protocol, not the SA380TX.
Data Available
| Parameter | Units | RS485 | 4-20mA | Digital VFC | Notes |
|---|---|---|---|---|---|
| Instantaneous Resistance to Earth | k Ohm | This is the last reading of Resistance-to-Earth taken by the isometer | |||
| Alert Levels | k Ohm | The isometer permits two configurable alert thresholds. These levels are both reported | |||
| Alarm Status | Digital | Reports if either alarm level has been breached | |||
| Fault Repeat Relay Status | Digital | Reports if output fault relay has been energised. Essentially mirrors alarm status | |||
| Connection Error | Digital | Set to UP or TRUE is not RS485 data has been received from the isometer for 7 minutes. | |||
| AC, DC+, DC- Fault | Digital | For DC Systems, Indicates which leg is experiencing the worst fault. For AC systems, only the AC flag will be asserted. | |||
| Fault Repeater Output | Digital | Where a fault repeater is provided and a single isometer monitors a multiple-feeder arrangement, a digital volt-free-contact output is provided for each feeder. The feeder experiencing the worst fault will have its contact closed. |
These parameters can be continuously monitored to perform long-term trend analysis of cable condition, to alert maintainers of faults that require intervention, and to aid diagnosis of the fault type and location.
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Wiring
RS485
Configure the network as shown below using twisted pair cable. Note the use of termination resistors at each end of the link. These are only strictly required for very long cable runs exceeding 1 km in length.
| Info |
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Note that if the isometer is built into a Network Rail style cubicle arrangement, the RS485 |
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connection are brought-out at the base of the cubicle through the terminal block positions 18 and 19 If connecting directly to the isometer. Connect straight to terminals B and A. |
4-20mA
Not recomended, but could be employed to connect multiple bender units to a single TX by utilising spare analogue inputs.
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