Description
The Macromatic ARP120A8R is a heavy-duty 8-pin plug-in duplex alternating relay designed to optimize load balancing and sequencing for dual-motor or dual-pump installations. Operating on a 120 VAC control supply, this relay delivers specialized Sequence On – Simultaneous Off (S.O.S.O.) operational logic, combining the functions of an alternating relay, control relay, and auxiliary interlock contacts into a single compact control module.
Engineered specifically for 3-float switch systems (OFF, LEAD, and LAG), the ARP120A8R ensures that two loads are energized sequentially during heavy demand but remain operating together until the OFF switch opens, de-energizing both loads simultaneously. On subsequent cycles, the relay toggles the starting lead load (Load 1 vs. Load 2) to equalize wear across both pumps or motors. Built-in logic protects against premature failure of both the OFF and LEAD switches. A front-accessible 3-position selector switch allows technicians to choose standard ALTERNATE mode or lock either LOAD 1 or LOAD 2 to energize first, while dual LED indicators provide clear visual confirmation of relay output status.
Key Features
- Sequence On – Simultaneous Off (S.O.S.O.) Logic: Controls two loads using three float switches (OFF, LEAD, LAG) to energize loads sequentially and shut them off simultaneously.
- Automatic Load Equalization: Toggles lead/lag operational order on each cycle to distribute runtime evenly across dual pump or motor systems.
- 3-Position Selector Switch: Low-profile front switch allows selection of standard ALTERNATE operation or locking either LOAD 1 or LOAD 2 as the primary lead load.
- Built-In System Protection: Integrated control logic safeguards pumping systems against failures of the OFF and LEAD level switches.
- 5A DPDT Output Contacts: Heavy-duty Double Pole Double Throw output relay rated for 5 A @ 120 VAC / 24 VDC (B300 pilot duty).
- Industry-Standard 8-Pin Plug-In Base: Mounts directly into standard 8-pin octal sockets to simplify panel installation and space management.
- Dual Status LEDs: High-visibility LEDs give clear visual feedback on relay state and active output status.
Specifications
| Technical Specification | Detail |
|---|---|
| Product Model | ARP120A8R |
| Brand / Series | Macromatic (ARP Series) |
| Product Type | Duplex Alternating Relay (Sequence On – Simultaneous Off) |
| Control Voltage | 120 VAC (+10/-15% at 50/60 Hz) |
| Operating Function | Duplex Sequence On – Simultaneous Off (S.O.S.O.) |
| Output Contact Configuration | 5A DPDT |
| Output Contact Rating | 5 A @ 120 VAC / 5 A @ 24 VDC, Pilot Duty B300 |
| Selector Switch Modes | 3 Positions: LOAD 1 (Always First), ALTERNATE, LOAD 2 (Always First) |
| Control Inputs Required | 3 Switches (OFF, LEAD, LAG float switches) |
| Power Burden / Load | Less than 3 VA |
| Mounting / Enclosure Style | Plug-In (Requires standard 8-pin octal socket) |
| Status Indication | Dual LEDs (Relay & Load Status) |
| Operating Temperature Range | -18°F to 149°F (-28°C to 65°C) |
| Storage Temperature Range | -40°F to 149°F (-40°C to 65°C) |
| Lifespan | Mechanical: 10,000,000 operations | Full Load: 100,000 operations |
| Primary Applications | Duplex wastewater lift stations, sump pump control panels, dual air compressor systems, commercial water booster systems |
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