| Data Sheet Extract | Caledon | |
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| INSTRUMENTS | MODBUS RTU TRUE RMS CURRENT AND VOLTAGE DATA ACQUISITION MODULE | ||
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DIN rail mounted |
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MODBUS RTU Slave | |
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True RMS readings | |
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Suitable for load monitoring with phase angle or burst fire control | |
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24V DC power supply | |
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Galvanically isolated comms port | |
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For use with either 1A or 5A Current transformer secondaries |
The module accepts 3 current inputs, 3 non-isolated single ended voltage inputs, and 3 (transformer) isolated voltage inputs. The module acts as a Modbus RTU slave, with a galvanically isolated communications port. The port may be connected either as RS422 with separate Tx and Rx pairs, or RS485 with a single pair for Tx and Rx
Two sets of values are transmitted for each voltage or current signal:-
| 1 | This is simply the RMS value, continuously updated. |
| 2 | This reading is processed for monitoring of load voltage or current for use with burst fire control. The input signal is monitored over a timed period (either 15 seconds or 35 seconds, selectable by the digital input). At the end of the timed period the maximum RMS value recorded in the period is transferred to the register for access by the comms. This results in a steady reading of voltage or current when the thyristor stack is either on permanently, or burst firing with a period less than the timed period above, and a reading of near zero when the stack is permanently off, or off for longer than the timed period. |
We should be pleased to consider custom variants of this module - please let us know your requirements.
Power Supply
The module requires a nominal 24V DC power supply, limits of range 20 to 28V. The supply should be fitted with a 250mA fuse. Current consumption is nominally 120mA
Enclosure
DIN rail mounted enclosure with clear polycarbonate cover, size 220mm long x 110mm high x 80mm deep when mounted on 35 x 8 mm symmetrical DIN rail.
Electrical connections are to screw terminals, with rising clamp connectors, suitable for cables up to 2.5mm2.
Environmental
0-50oC operating temperature range. 0-95% RH, non condensing.
Download datasheet (.pdf)
