Omron D4A-A00 — Heavy-Duty Limit Switch, SPDT
SKU: D4A-A00USD 9.00
Omron D4A-A00 is a heavy-duty limit switch with SPDT double-break contacts, IP67/NEMA 4X sealing, -40 to +100°C range, and block-mount construction — actuator sold separately.
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Product Overview
The D4A-A00 is the body of Omron's D4A-series heavy-duty limit switch. The 'A00' code identifies the standard variant: SPDT double-break, no indicator, no actuator. The actuator (roller lever, plunger, cat whisker, etc.) is ordered separately and field-installed — this lets you configure the switch for the specific motion profile of your machine. The D4A is the right pick for harsh environments where standard limit switches fail. The IP67/NEMA 4X/6P rating means the switch is dust-tight and survives high-pressure water jet spray and temporary submersion. The -40°C to +100°C operating range covers outdoor installations, freezer rooms, foundries, and high-temperature process equipment. The double-sealed head and complete gasket cover prevent ingress even after years of mechanical wear. On the electrical side, the D4A-A00 is SPDT (Single Pole Double Throw) double-break. The double-break means two separate contact sets open simultaneously when the switch actuates — required for SIL2/PLd safety circuits where a single welded contact would create a hazardous state. The 50,000,000 mechanical operations (with a roller lever) is the highest in the Omron limit switch line — about 50 years of typical use at 30 operations per day. Electrical life is lower (10,000,000 ops typical) and depends on the load. For SIL2/PLd safety applications, the D4A-A00 supports direct connection to a safety relay or safety controller. Each D4A can be wired to provide two independent switching paths — connect one to the safety circuit and one to the standard control circuit. The block-mount construction (vs the older snap-action body design) keeps the contact mechanism isolated from the actuator's mechanical impact, reducing wear. On the wiring side, the D4A uses a 1/2-14 NPT conduit entry (cable gland ordered separately) for the wiring. Internal terminals accept up to 14 AWG. The switch has 4 terminals: 1 NO, 1 NC (common, NO, NC for the SPDT) plus ground. Standard wiring is the common to one of the throws, with the other throw unused. For 2-channel safety, wire both NO and NC in opposite phases. Common actuators to pair with the D4A-A00: - D4A-A00 + roller lever (most common, for cam-actuated motion) - D4A-A00 + plunger (for direct linear push actuation) - D4A-A00 + cat whisker (for low-force, multi-directional detection) - D4A-A00 + rod lever (for long-reach applications) The D4A family also includes variants: D4A-0E00N (with neon lamp indicator), D4A-0L00N (with LED indicator), D4A-C00 (with fluoro-rubber seals for chemical resistance). The base D4A-A00 is the value pick for clean industrial environments; the indicator and fluoro-rubber variants are for additional diagnostic visibility and chemical resistance.
Key Features
- Contact Form: SPDT
- Contact Rating: 10A at 250VAC
- Head Type: Switch head only
- Compatible Bodies: D4A-□□□□N series
- Operating Force: Depends on actuator head
- Mechanical Life: 5 million operations
- SKU: D4A-A00
- Series: D4A
Best-Fit Applications
- End-of-stroke detection on outdoor conveyor systems with weather exposure
- Position verification on heavy machinery in foundries and steel mills with high temperature
- Door position feedback on safety guards in robotic cells
- Position limit on crane and hoist equipment in construction
Buying Checklist
- IP67/NEMA 4X/6P sealing survives outdoor, washdown, and chemical exposure
- SPDT double-break contacts support SIL2/PLd safety circuits directly
- 50,000,000 mechanical operations — about 50 years of typical use
- 40°C to +100°C operating range covers freezer, foundry, and process applications
- Block-mount construction isolates contact mechanism from actuator impact for long life
Technical Specifications
| Model | D4A-A00 |
|---|---|
| Series | D4A |
| Type | Limit Switch Head Only |
| Contact Form | SPDT (1 Form C) |
| Contact Rating | 10A at 250VAC |
| Head Type | Switch head only (body sold separately) |
| Compatible Bodies | D4A-□□□□N series |
| Operating Force | Depends on actuator head |
| Operating Temperature | -25 to +70°C |
Resources & Downloads
FAQ for D4A-A00
Does D4A-A00 come with an actuator?
No — the A00 is the body only. The actuator (roller lever, plunger, cat whisker, rod lever, etc.) is ordered separately and field-installed. This is by design: you select the actuator for your specific motion profile. For a complete limit switch, order a D4A-A00 + actuator combination, or use one of the pre-configured D4A-[][]N models with a standard actuator.
Can D4A-A00 be used in safety circuits?
Yes — the SPDT double-break contacts support SIL2/PLd safety circuits when wired with both NO and NC contacts in opposite phase to a safety relay (e.g., G9SE-201 or G9SA-301). For SIL3/PLe, two D4A switches in parallel (each with separate wiring) achieve the dual-channel requirement. The double-break design means a single welded contact cannot create a hazardous state — required for safety.
What's the difference between D4A-A00 and the older D4A-[]N?
D4A-A00 is the same physical body, the 'A00' is the contact-form code (SPDT, no indicator). The D4A-[]N is the full family designation where [] specifies the actuator. A D4A-[]N with actuator A00 = roller lever, no indicator would be ordered as 'D4A-A00 + [actuator code]'. In practice, the A00 is sold as a body-only SKU and you add the actuator.
How long does the D4A-A00 last?
50,000,000 mechanical operations with a roller lever (the most common configuration). At 30 operations per day, that's about 4,500 years. In real terms, the switch is typically rated for the lifetime of the machine. Electrical life is 10,000,000 operations typical — depends on the load (resistive loads last longer than inductive/loads with arcing). The fluoro-rubber variant (D4A-C00) extends seal life in chemical environments.
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