Power Supplies

Power Supplies

Compact I/O power supplies (1769-PA2, -PB2, -PA4, -PB4) provide 5V DC and 24V DC power for Compact I/O modules. Include a power supply module in each bank of Compact I/O modules (unless the modules are connected directly to a MicroLogix 1500 base unit). Up to eight I/O modules can be installed on either side of the power supply, for a maximum of 16 modules, within the load capacity of the power supply.

1769 Compact I/O power supplies distribute power from either side of the power supply. For example, a 2A at 5V DC power supply can provide 1A to the right side of the power supply and 1A to the left or 2A in one direction. The maximum amount of current the system supports in one direction is 2A at 5V DC and 1A at 24V DC.

When connecting a 1769 expansion I/O power supply to a MicroLogix 1500 base unit, you must use a 1769 I/O expansion cable.

Specifications

	1769-PA2	1769-PB2	1769-PA4	1769-PB4
Input Voltage, Nom.	120V AC or 240V AC	24V DC	120V AC or 240V AC	24V DC
Input Voltage Range	85…265V AC	19.2…31.2V DC	85…132V or 170…265V AC	19.2…31.2V DC
Real Input Power, Max.	44 W	50 W at 24V DC	90 W	100 W at 24V DC
Apparent Input Power, Max.	100 VA at 120V AC 130 VA at 240V AC	50 VA at 24V DC	200 VA at 120V AC 240 VA at 240V AC	100 VA at 24V DC
Typical Apparent Input Power at Full Load	80 VA	50 VA at 24V DC	160 VA	100 VA at 24V DCA
Line Loss Ridethrough	10 ms…10 s		5 ms…10 s
Frequency	47…63 Hz	DC	47…63 Hz	DC
Backplane Output Current, 0…55 °C, Max.	2 A at 5V DC 0.8 A at 24V DC 250 mA at 24V DC User	2 A at 5V DC 0.8 A at 24V DC	4 A at 5V DC 2 A at 24V DC	4 A at 5V DC 2 A at 24V DC
Backplane Output Current, 55…60 °C, Max.	2 A at 5V DC 675 mA at 24V DC 200 mA at 24V DC User	2 A at 5V DC 0.8 A at 24V DC	4 A at 5V DC 1.7 A at 24V DC	4 A at 5V DC 1.7 A at 24V DC
Fuse	Front Access
Dimensions (HxWxD), Approx.	118 x 70 x 87 mm (4.65 x 2.76 x 3.43 in.) Height including mounting tabs is 138 mm (5.43 in)
Weight	0.5 kg (1.2 lb)		0.6 kg (1.4 lb)
Operating Temperature	0…60 °C (32…140 °F)
Nonoperating Temperature	-40…85 °C (-40…185 °F)
Relative Humidity	5…95% noncondensing
Agency Certification (when product is marked)	c-UL-us certified (under CSA C22.2 No. 142) CE compliant for all applicable directives
Hazardous Environment Class	Class I, Division 2, Hazardous Location, Groups A, B, C, D certified for U.S. and Canada

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.