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Macromatic CAH05A1AD 240V AC Current Sensing Relay: 0.5–5A, 1-Second Startup Delay
Encapsulated CAH Series overcurrent and undercurrent monitoring relay with an adjustable 0.5–5A sensing range, 0.15–7 second trip delay, integrated toroidal current transformer, red fault LED, and 10A SPDT output.
Why Choose the Macromatic CAH05A1AD Current Sensing Relay?
The Macromatic CAH05A1AD monitors AC current for either an overcurrent or undercurrent condition. A selector switch chooses the monitoring mode, while separate adjustments set the 0.5–5A fault threshold and 0.15–7 second trip delay. This model uses a 1 second startup sensing delay, allowing its response to be matched to the equipment startup profile.
The integrated toroidal current transformer lets the monitored conductor pass through the relay housing without a separate external sensor. An encapsulated enclosure supports demanding industrial environments, and the red LED provides a clear visual fault indication for process controls, motors, heaters, lamps, and load-monitoring systems.
📈 0.5–5A Adjustable Range
Set the current threshold to match the normal operating range of the monitored load
↕️ Over / Under Selection
One relay can detect current above or below the chosen fault trip point
⏱️ 1-Second Startup Delay
Waits 1 second after power is applied before monitoring, helping ignore startup current conditions
🛡️ Encapsulated Housing
Protects the relay electronics for use in harsh industrial operating conditions
⚠️ Confirm the Startup Sensing Delay
Macromatic CAH05A1AD has 1 second startup sensing delay. Current monitoring begins after the fixed 1 second delay expires.
Choose the startup delay that allows the connected motor or load to reach normal operating current without creating unwanted fault trips.
📋 Overcurrent and Undercurrent Operation
Overcurrent mode: The relay energizes when measured current stays above the selected fault threshold longer than the adjustable trip delay. It remains energized until current falls below the reset level.
Undercurrent mode: The relay energizes when measured current stays below the selected fault threshold longer than the trip delay. It de-energizes after current rises above the reset level.
Fault indication: The red LED illuminates when the relay detects a fault condition.
Key Features & Benefits
- Monitors two fault types: Selector-controlled overcurrent or undercurrent operation covers load increase and load-loss conditions
- Simplifies current sensing: The built-in through-hole toroid eliminates the need to mount and wire a separate current transformer
- Filters short disturbances: Adjustable 0.15–7 second trip delay helps prevent brief current changes from triggering an output
- Matches startup behavior: Waits 1 second after power is applied before monitoring, helping ignore startup current conditions
- Provides local diagnostics: A red LED makes detected faults visible during setup and troubleshooting
- Supports demanding locations: Encapsulated construction protects internal electronics from harsh conditions
Technical Specifications
| Part Number | CAH05A1AD |
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| Brand | Macromatic |
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| Series | CAH |
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| Relay Function | Selectable overcurrent / undercurrent monitoring |
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| Monitored Current | AC current |
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| Current Monitor Range | 0.5–5A adjustable |
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| Trip Time Delay | 0.15–7 seconds adjustable |
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| Startup Sensing Delay | 1 second |
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| Input Voltage | 240V AC |
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| Input Voltage Tolerance | +10% / -15% of nominal |
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| Load | 2VA |
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| Output | 10A SPDT |
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| Output Contact Ratings | 10A at 240V AC general purpose; 8A at 28V DC resistive; 1/4 HP at 120/240V AC; B300 pilot duty |
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| Current Sensing | Toroidal, through-hole wiring |
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| Setting Accuracy | Minimum: +0% / -50%; Maximum: +10% / -0% |
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| Maximum Allowable Current | 25A-turns continuous; 150A inrush for 10 seconds |
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| Trip-Point Hysteresis | -5% overcurrent; +5% undercurrent |
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| Time Delay on Reset, Relay Off | 100 ms |
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| Reset Time | 400 ms |
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| Operating Temperature | -28°C to 65°C (-18°F to 149°F) |
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| Storage Temperature | -40°C to 85°C (-40°F to 185°F) |
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| Mechanical Life | 10,000,000 operations |
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| Full-Load Life | 100,000 operations |
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| Mounting | Surface mount with two #6 screws |
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| Termination | 0.25 in. male quick-connect terminals |
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| Dimensions | 3.5 in. H × 2.5 in. W × 1.5 in. D |
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| Approvals | UL and cUL Recognized |
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🏭 Typical Applications
Motor protection: Detect locked rotors, overload conditions, or loss of mechanical load
Process control: Verify that pumps, conveyors, fans, and other equipment are drawing expected current
Heater and lighting monitoring: Detect an open heater element, lamp failure, or interrupted circuit
🔧 Installation Notes
Pass the monitored conductor through the toroidal opening. Do not route the complete supply circuit through the opening if the opposing conductor would cancel the measured magnetic field.
Mount the relay with two #6 screws and connect control wiring using the 0.25 in. male quick-connect terminals. Follow the installation manual for terminal assignments and adjustment procedures.
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