1746-OW16 — SLC 500 16-Point Relay Output Module

The 1746-OW16 is a 16-point relay output module for the SLC 500 modular chassis system. Each output is a Form A (normally open) relay contact, grouped into four sets of four points sharing a common terminal per group. It switches AC or DC loads up to the contact rating, making it the standard choice in SLC 500 panels for driving solenoid valves, contactor coils, pilot lights, and other field devices that need voltage flexibility beyond what a transistor output module provides.

Specifications

Parameter	Value
Part Number	1746-OW16
Platform	SLC 500 (1746 series)
Output Points	16
Contact Type	Form A (Normally Open)
Output Groups	4 × 4 points, separate commons per group
Rated Voltage (AC)	240V AC max
Rated Voltage (DC)	125V DC max
Rated Current	2 A per point (resistive)
Max Group Current	8 A per group of 4
Backplane Current (5V)	160 mA
Operating Temperature	0°C to 60°C
Standards	UL 508, CE

Relay Density in SLC 500 Panels

Sixteen relay points in one slot is a practical density for SLC 500 systems where a meaningful portion of the machine's outputs are AC-switched or need the voltage flexibility relay contacts provide. The four-group structure — four points per common — lets different groups run from different supplies or circuits without interaction, while keeping wiring manageable: four commons to land rather than sixteen individual returns.

This module remains in active service across a large installed base of legacy SLC 500 panels. For facilities maintaining these systems, the 1746-OW16 is one of the higher-turnover spare parts given how frequently relay contacts wear out from inductive load switching compared to the chassis, processor, or input modules around it.

Load Planning and Contact Protection

Each group of four shares one common terminal — plan the supply wiring so each group's total simultaneous current stays within the 8A group limit, even though individual points are rated at 2A.
For inductive loads (solenoid coils, contactor coils, relay coils), fit a suppressor across the load: an MOV or RC snubber for AC circuits, a flyback diode for DC circuits. This single step extends relay contact life substantially by absorbing the back-EMF spike that occurs on each switch-off.
Different groups can be wired to different voltage circuits — one group on 24V DC, another on 120V AC — since the groups don't share a common reference with each other.
External fusing per group, sized to the group's expected load current, protects field wiring independently of the module's own (non-fused) relay contacts.

FAQ

Q: Can the four output groups switch different voltage types simultaneously?

Yes. Since each group has its own common terminal with no shared reference to the other groups, one group can switch 120V AC loads while another switches 24V DC loads on the same module without interference.

Q: What is the expected contact life under typical industrial loading?

Mechanical life is rated in the millions of operations; electrical life at full rated load is in the range of 100,000+ operations, with significant variation based on load type. Resistive loads at low current extend life well beyond the rated figure; inductive loads without suppression shorten it.

Q: Is the 1746-OW16 hot-swappable in a running SLC 500 chassis?

The SLC 500 platform does not officially support hot insertion or removal of standard I/O modules. Best practice is to de-energize the chassis before replacing this or any other 1746 module.

Q: Can this module drive a motor starter coil directly?

Yes, provided the starter coil's voltage and current draw fall within the module's per-point and per-group ratings. Fit appropriate suppression across the coil, since contactor coils are a classic inductive load that benefits significantly from a snubber or diode.

1746-OW16 Digital Output Module 1746OW16 Genuine New