Technical data

ManualsBrandsAllen-Bradley ManualsAdapter1794ASB Series B

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Publication 1794-2.1 - January 2000

FLEX I/O and FLEX Integra Product Data

24V dc 8 Relay Sink/Source Output Module Cat. No. 1794-OW8 121

Simplified Schematic of Relay Module

Load power can be obtained from a variety of sources, and can range

from +5V dc to 240V ac. Make certain that only 24V dc is applied to

the module power terminals on the module terminal base

ATTENTION

Do not attempt to increase load current or wattage

capability beyond the maximum rating by

connecting 2 or more outputs in parallel. The

slightest variation in relay switching time may cause

one relay to momentarily switch the total load

current.

Apply only +24V dc power to the power terminals

on the terminal base unit. Make certain that all relay

wiring is properly connected before applying any

power to the module.

Total current draw through the terminal base unit is

limited to 10A. Separate power connections to the

terminal base unit may be necessary.

Specifications - 1794-OW8

Outputs per Module 8 Form A isolated (normally open)

electromechanical relays

Module Location Cat. No. 1794-TBNF, -TB3, -TB3S, -TB2 or -TBN

Terminal Base Unit

Off-State Leakage

Current (max at 240V ac)

1mA thru snubber circuit

Output Voltage Range (load

dependent)

5-30V dc @ 2.0A resistive

48V dc @ 0.5A resistive

125V dc @ 0.25A resistive

125V ac @ 2.0A resistive

240V ac @ 2.0A resistive

Output Current Rating

(at rated power)

Resistive

2A @ 5-30V dc

0.5A @ 48V dc

0.25A @ 125V dc

2A @ 125V ac

2A @ 240V ac

Inductive

2.0A steady state @ 5-30V dc, L/R = 7ms

0.5A steady state @ 48V dc, L/R = 7ms

0.25A steady state @ 125V dc, L/R = 7ms

2.0A steady state, 15A make @ 125V ac,

PF = cos θ = 0.4

2.0A steady state, 15A make @ 240V ac,

PF = cos θ = 0.4

Power Rating

(steady state)

250W max. for 125V ac resistive output

480W max. for 240V ac resistive output

60W max. for 30V dc resistive output

24W max. for 48V dc resistive output

31W max. for 125V dc resistive output

250VA max. for 125V ac inductive output

480VA max. for 240V ac inductive output

60VA max. for 30V dc inductive output

24VA max. for 48V dc inductive output

31VA max. for 125V dc inductive output

120V

24V

48V

240V

24V

120V

240V

125V

Representative Examples of Various Relay Loads

Relay Load Contact Wiring

+24V

Return

40155

Isolation Voltage

Between any 2 sets

of contacts

Customer load to logic

Customer load to 24V

dc supply

Customer 24V dc supply

to logic

2550V dc for 1s

850V dc for 1s

Output Signal Delay

OFF to ON

ON to OFF

8ms maximum (time from valid output on signal to

relay energization by module)

26ms maximum (time from valid output off

signal to relay deenergization by module)

Flexbus Current (max) 69mA @ 5V dc

Power Dissipation Maximum 5.5W

Thermal Dissipation Maximum 18.8 BTU/hr

Indicators (field side

indication, logic driven)

8 yellow status indicators

Keyswitch position 9

Initial Contact Resistance 30mΩ

Switching Frequency 1 operation/3s (0.3Hz at rated load) max

Operate/Release Time Maximum 10ms

Bounce Time 1.2ms (mean)

Minimum Contact Load 100µA at 100mV dc

Expected Life of

Electrical Contacts

Minimum 100,000 operations @ rated loads

Fusing

Use a 1794-TBNF with a 3.0A Littelfuse 239003

Max Inrush Current 15A

General Specifications

External dc Power

Supply Voltage

Voltage Range

Supply Current

24V dc nominal

19.2 to 31.2V dc (includes 5% ac ripple)

125mA maximum

Dimensions HxWxD 46mm x 94mm x 53mm (1.8in x 3.7in x 2.1in)

Environmental Conditions

Operational Temperature

Storage Temperature

Relative Humidity

Shock Operating

Non-operating

Vibration

0 to 55

C (32 to 131

-40 to 85

C (-40 to 185

5 to 95% noncondensing

12g peak acceleration, 11(±1)ms pulse width

50g peak acceleration, 11(±1)ms pulse width

Tested 2g @ 10-500Hz per IEC 68-2-6

Conductors Wire Size