DC Power Supply Characteristics and Wiring
This section provides the characteristics and the wiring diagrams of the DC power supply.
If the specified voltage range is not maintained, outputs may not switch as expected. Use appropriate safety interlocks and voltage monitoring circuits.
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FIRE HAZARD |
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oUse only the correct wire sizes for the maximum current capacity of the I/O channels and power supplies. |
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Failure to follow these instructions will result in death or serious injury. |
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UNINTENDED EQUIPMENT OPERATION |
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Do not exceed any of the rated values specified in the environmental and electrical characteristics tables. |
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Failure to follow these instructions can result in death, serious injury, or equipment damage. |
The M251 Logic Controllerand associated I/O (TM2, TM3, with a nominal voltage of 24 Vdc. The 24 Vdc power supplies must be rated Safety Extra Low Voltage (SELV) or Protective Extra Low Voltage (PELV) according to IEC 61140. These power supplies are isolated between the electrical input and output circuits of the power supply.
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POTENTIAL OF OVERHEATING AND FIRE |
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oDo not connect the equipment directly to line voltage. oUse only isolating PELV power supplies to supply power to the equipment1. |
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Failure to follow these instructions can result in death, serious injury, or equipment damage. |
1 For compliance to UL (Underwriters Laboratories) requirements, the power supply must also conform to the various criteria of NEC Class 2, and be inherently current limited to a maximum power output availability of less than 100 VA (approximately 4 A at nominal voltage), or not inherently limited but with an additional protection device such as a circuit breaker or fuse meeting the requirements of clause 9.4 Limited-energy circuit of UL 61010-1. In all cases, the current limit should never exceed that of the electric characteristics and wiring diagrams for the equipment described in the present documentation. In all cases, the power supply must be grounded, and you must separate Class 2 circuits from other circuits. If the indicated rating of the electrical characteristics or wiring diagrams are greater than the specified current limit, multiple Class 2 power supplies may be used.
This table shows the characteristics of the DC power supply required for the controller:
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Characteristic |
Value |
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Rated voltage |
24 Vdc |
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Power supply voltage range |
19.2...28.8 Vdc |
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Power interruption time |
10 ms at 24 Vdc |
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Maximum inrush current |
50 A |
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Power consumption |
32.6 W, max. 40.4 W(1) |
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Isolation |
between DC power supply and internal logic |
Not isolated |
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between DC power supply and protective earth ground (PE) |
500 Vac |
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(1) Controller + 7 TM3 expansion modules |
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The duration of power interruptions where the M251 Logic Controller is able to continue normal operation varies depending upon the load to the power supply of the controller, but a minimum of 10 ms is maintained as specified by IEC standards.
When planning the management of the power supplied to the controller, you must consider the power interruption duration due to the fast cycle time of the controller.
There could potentially be many scans of the logic and consequential updates to the I/O image table during the power interruption, while there is no external power supplied to the inputs, the outputs or both depending on the power system architecture and power interruption circumstances.
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UNINTENDED EQUIPMENT OPERATION |
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oIndividually monitor each source of power used in the controller system including input power supplies, output power supplies and the power supply to the controller to allow appropriate system shutdown during power system interruptions. oThe inputs monitoring each of the power supply sources must be unfiltered inputs. |
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Failure to follow these instructions can result in death, serious injury, or equipment damage. |
DC Power Supply Wiring Diagram
This figure shows the power supply terminal block removal procedure:
The following figure shows the wiring of the DC power supply:
* Type T fuse
For more information, refer to the 5.08 pitch Rules for Removable Screw Terminal block.
