Selectable Overcurrent and Undercurrent Monitoring
In overcurrent mode, the relay energizes when the monitored AC current remains above the fault trip setting for longer than the adjusted trip delay. It stays energized until the current falls below the reset level. In undercurrent mode, the relay energizes when current remains below the fault trip setting for longer than the trip delay, then de-energizes when current rises above the reset level.
Timing and Fault Indication
The CAH05A1BD combines a fixed 1 second startup sensing delay with an adjustable 0.5–50 seconds fault trip delay. The startup delay and trip delay serve separate timing functions; account for both when selecting the relay for the equipment’s operating sequence. A red LED indicates a detected fault. Trip point hysteresis is −5% for overcurrent sensing and +5% for undercurrent sensing. The relay has a 100 ms time delay on reset (relay OFF) and a 400 ms reset time.
Features and Benefits
- An integrated toroidal current transformer provides through-hole wiring for AC current monitoring.
- Selectable overcurrent or undercurrent operation supports different fault-monitoring requirements.
- The encapsulated housing suits industrial installations with harsh operating conditions.
- A red LED provides local fault indication during equipment checks.
- The SPDT output includes general-purpose, resistive, horsepower, and B300 pilot-duty ratings.
- Surface mounting and male quick-connect terminals support control-panel installation.
Applications
Use the CAH05A1BD in process control systems that monitor AC current for equipment fault conditions. Overcurrent monitoring can help identify locked-rotor conditions, while undercurrent monitoring can indicate load loss or an open heater or lamp circuit. Select the monitoring mode, trip current, and timing settings to match the normal current profile of the equipment.
Mounting and Wiring
The relay mounts to a surface with two #6 screws and uses 0.25-inch male quick-connect terminals. Its overall dimensions are 3.5 inches high × 2.5 inches wide × 1.5 inches deep. Route the monitored conductor through the integrated current transformer and follow the installation manual for wiring and adjustment.
Selection Notes
Match the 240 V AC supply requirement to the control circuit and verify the applicable output contact rating for the connected load. The adjustable 0.5–5 A monitor range is separate from the maximum allowable sensed current. Check the steady-state and inrush limits, timing settings, and operating temperature before installation.
Installation Manual
Macromatic CAH Series Relay Installation Manual
