1762-OW8 — 1200 Series 8-Point Relay Output Expansion Module

The 1762-OW8 is an 8-point relay output expansion module for the 1762-series (1200 Series) controller expansion bus. Each of the eight outputs is a Form A (normally open) relay contact rated at 240V AC or 30V DC at 2A. All eight contacts are individually isolated from each other — each relay circuit can switch a different voltage from a different supply reference. For small controllers whose onboard relay outputs are already committed or whose output types don't match all field devices, the 1762-OW8 adds 8 additional relay contacts with the voltage flexibility that transistor outputs can't provide.

Specifications

Parameter	Value
Part Number	1762-OW8
Platform	1762-series expansion bus
Output Points	8
Contact Type	Form A (Normally Open)
Rated Voltage (AC)	240V AC max
Rated Voltage (DC)	30V DC max
Rated Current (resistive)	2 A per point
Isolation	Point-to-point and point-to-backplane isolated
Electrical Life (full load)	100,000 operations
Mechanical Life	10 million operations
Backplane Current (5V)	180 mA
Backplane Current (24V)	95 mA
Operating Temperature	0°C to 60°C
Standards	UL 508, CE, IEC 61131-2

Where Relay Outputs Fit

Transistor outputs are faster, don't wear out, and handle high-cycle 24V DC loads well. Relay contacts handle everything else — 120V AC pilot lights, 240V AC solenoid valves, 120V AC contactor coils, 24V DC loads that need circuit isolation from the controller's supply, and any combination of AC and DC loads in the same module. The individual contact isolation on the 1762-OW8 is what makes this practical: output 0 can switch a 120V AC solenoid while output 1 simultaneously switches a 24V DC indicator and output 2 controls a 240V AC pilot lamp, all from one module without any shared common between circuits.

For 1762-series installations where the controller's onboard outputs are mixed relay and transistor and the transistors are fully allocated to high-cycle 24V DC loads, the OW8 expansion handles the remaining relay-required outputs without requiring a separate relay panel or interposing relay bank.

Contact Life and Load Management

The 100,000 operation electrical life at full rating (2A, 240V AC) is the most conservative figure. Actual contact life depends heavily on load type:

Resistive loads at low current (LED indicators, pilot lamps): life typically exceeds the rated figure significantly. A 50 mA LED imposes almost no arc stress per operation.
Inductive loads (solenoids, contactor coils): the inductive energy stored in the coil generates an arc on contact opening that erodes the silver contact surface faster than resistive loads. Fit a MOV or RC snubber across AC inductive loads; a flyback diode across DC inductive loads. This extends contact life considerably and protects against voltage transients reaching the module.
High-cycle outputs: relay outputs cycling more than 10–20 times per minute on the same contact will exhaust mechanical and electrical life faster than infrequent-switching contacts. Move high-cycle loads to transistor outputs and reserve the relay contacts for low-cycle AC and high-voltage circuits.

The 1762 expansion bus does not support hot-swap. De-energize the system before adding or removing the 1762-OW8. The controller will lose its I/O connection briefly during bus reconfiguration if the module is inserted or removed under power.

FAQ

Q: Can the 1762-OW8 switch 277V AC loads (common in North American lighting panels)?

No. Maximum rated voltage is 240V AC. For 277V AC switching, an external relay rated for that voltage is required, with the 1762-OW8 contact driving the external relay coil at a lower voltage.

Q: How many 1762-OW8 modules can be added to one controller?

The 1762-series expansion bus supports up to 6 expansion modules total per controller. The combination of module types (digital I/O, analog, relay, etc.) is flexible within that 6-module limit.

Q: Are the 8 contacts individually fused inside the module?

No internal fusing. Each output circuit should have an external fuse or circuit breaker on its load supply line for branch circuit protection and fault isolation. Without per-circuit fusing, a wiring fault on one output could affect other outputs sharing the same supply phase.

Q: Can Form A contacts be used as normally closed by inverting the output logic in the program?

The contact is mechanically normally open — with the output bit set to 0, the contact is open; with the bit set to 1, the contact closes. To achieve normally closed behavior (contact closed when output bit is 0), set the output bit to 1 continuously and invert the logic in the ladder program. The contact still opens when commanded — just the logic is inverted. Note this means the contact is energized continuously in the "normal" state, which consumes the relay's electrical life at the same rate as a frequently-switching output.

1762-OW8 New Sealed 1762OW8 Micrologix 8PT VAC/VDC Relay Output Module