Power Supplies
1746 Power SuppliesSLC 500 modular systems provide separate power supplies which must be mounted directly on the left end of the 1746 I/O chassis. Seven power supplies are available to meet your system power requirements: three AC -input power supplies and four dc-input power supplies.
Each chassis requires a power supply (which connects to the chassis without a separate cable) to provide power to the processor and each I/O slot. Consider future system expansion when selecting a power supply. Power supply features and benefits include:
- All power supplies have an LED that indicates proper supply power; monitoring this LED can tell you at a glance whether your supply is operating properly.
- Supplies have a hold-up time (the time the system is operational during a brief power loss) typically between 20 milliseconds and 3 seconds; power supplies are designed to withstand brief power losses without affecting the operation of the system. Actual duration of the power supply hold-up time depends on the number, type, and state of the I/O modules.
- On AC power supplies, you can select either 120V or 240V operation by setting a jumper; no special wiring is required.
Power Supplies
| Cat. No. | 1746-P1 | 1746-P2 | 1746-P3 | 1746-P4 | 1746-P5 | 1746-P6 | 1746-P7 |
| Input Voltage, Nom. | 120 or 220V AC | 120 or 220V AC | 24V DC | 120 or 220V AC | 125V DC | 48V DC | 12 or 24V DC |
| Input Voltage Range | 85…132V AC 170…265V AC |
85…132V AC 170…265V AC |
19.2…28.8V DC | 85…132V AC 170…265V AC |
90…146V DC | 30…60V DC | 10…30V DC |
| Inrush Current, Max. | 20 A | 20 A | 20 A | 45 A | 20 A | 20 A | 20 A |
| Real Input Power, Max. | 42 W | 70 W | 61 W | 92 W | 85 W | 100 W | 75 W at 24V 50 W at 12V |
| Apparent Input Power, Max. | 69 VA | 110 VA | — | 225 VA | — | — | — |
| Xformer Load, Max . | 106 VA | 175 VA | — | 230 VA | — | — | — |
| User Output Current | 0.2 A at 24V DC | 0.2 A at 24V DC | — | 1.0 A at 24V DC | 0.2 A at 24V DC | 0.2 A at 24V DC | — |
| User Output Voltage Range | 18…30V DC | 18…30V DC | — | 20.4…27.6V DC | 18…30V DC | 18…30V DC | — |
| Backplane Output Current |
2 A at 5V DC 0.46 A at 24V DC |
5 A at 5V DC 0.96 A at 24V DC |
3.6 A at 5V DC 0.87 A at 24V DC |
10 A at 5V DC 2.88 A at 24V DC (Total output power, including user, is 70 W max.) |
5 A at 5V DC 0.96 A at 24V DC |
5 A at 5V DC 0.96 A at 24V DC |
With 24V input: 3.6 A at 5V DC 0.87 A at 24V DC With 12V input: 2 A at 5V DC 0.46 A at 24V DC |
| Frequency | 47…63 Hz | 47…63 Hz | DC | 47…63 Hz | DC | DC | DC |
| Fuse⋆ | 3 A, 250V | 3 A, 250V | 5 A, 250V | none | none | none | none |
| Dimensions (HxWxD), Approx. |
140 x 58 x 145 mm (5.5 x 2.3 x 5.7 in.) | 140 x 74 x 145 mm (5.5 x 2.9 x 5.7 in.) | 140 x 74 x 145 mm (5.5 x 2.9 x 5.7 in.) | 140 x 110 x 145 mm (5.5 x 4.3 x 5.7 in.) | 140 x 74 x 145 mm (5.5 x 2.9 x 5.7 in.) | 140 x 85 x 145 mm (5.5 x 3.6 x 5.7 in.) | 140 x 85 x 145 mm (5.5 x 3.6 x 5.7 in.) |
| Weight | 0.9 kg (2.0 lb) | 1.1 kg (2.5 lb) | 1.1 kg (2.5 lb) | 1.1 kg (2.5 lb) | 0.4 kg (0.8 lb) | 1.1 kg (2.5 lb) | 1.1 kg (2.5 lb) |
| Operating Temperature | 0…60 °C (32…140 °F) (Current capacity derated 5% above 55 °C) |
0…60 °C (32…140 °F) | 0…60 °C (32…140 °F) (Current capacity derated 5% above 55 °C) |
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| Nonoperating Temperature | -40…85 °C (-40…185 °F) | ||||||
| Relative Humidity | 5…95% noncondensing | ||||||
| Wiring | two 14 AWG wires per terminal (maximum) | ||||||
| Location | 1746 chassis side | ||||||
| Certifications‡ | c-UL Class I Div 2 Hazardous, UL, CE | ||||||
| ⋆ Power supply fuse is intended to guard against fire hazard due to short-circuit conditions and may not protect the supply from damage under these conditions. ‡ When product is marked. See the Product Certification link at http://www.ab.com for Declarations of Conformity, Certificates, and other certification details. |
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Power Requirements and Transformer Sizing
Each AC -input power supply generates a shutdown signal on the backplane whenever the AC line voltage drops below its lower voltage limit. It removes the shutdown signal when the line voltage comes back up to the lower voltage limit. This shutdown is necessary to help ensure that only valid data is stored in memory.
The external transformer rating (in VA) of each power supply is greater than its real input power (in Watts) because a capacitor-input AC /DC supply draws power only from the peak of the AC voltage wave form. If the transformer is too small, it clips the peak of the sine wave; when the voltage is still above the lower voltage limit, the power supply will sense this clipped wave form as low voltage and could prematurely shut down modules in the chassis.
In the following graphs, we display the backplane power load on the vertical axis. Since these supplies have multiple outputs, the backplane power load is given in watts.
For the dc-input power supply, we display the input real power in watts. For each AC -input power supply, we display the input real power in watts, apparent power in VA, and the transformer load in VA, each in a separate graph.
- Use the real power value in watts for determining the amount of heat dissipation you will have inside the enclosure.
- Use the apparent power value in VA for estimating power cost.
- Use the transformer load value in VA of each power supply plus all other loads on a transformer to determine the required transformer size.
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