EM-M82A is a combined control and monitoring unit for automation devices with a terminal impedance between 15 and 300 Ω. Typical loads include solenoids, valves, contactors and resistive devices.
The unit controls the connected load through an internal relay while continuously monitoring the load circuit. It learns the normal line impedance and generates a fault alarm if the measured impedance changes outside the permitted range.
The EM-M82A monitors the impedance of the connected load circuit in both the energized and de-energized states. Two selectable impedance ranges are available:
The measuring range is selected using the configuration switches. After selecting the appropriate range, the normal line impedance is stored by pressing the programming button.
A fault alarm is generated if the measured load resistance decreases by more than 50% or increases by more than 100% relative to the learned reference value.
In standard learning mode, the device learns the normal electrical characteristics of the connected load circuit.
For non-linear loads, a special learning procedure can be used. In this mode, the de-energized and energized states are learned separately, allowing the monitoring limits to be based on the normal characteristics of each operating state.
The EM-M82A also monitors the operation of its internal control relay. The unit compares the control input state with the detected line voltage.
If the commanded state and the measured line condition do not correspond, the unit generates a fault alarm. This can help detect faults such as a control relay that does not operate as expected or an unexpected voltage condition on the load line.
The load is switched through an internal control relay. The relay can control loads with a continuous current of up to 1.5 A.
An integrated snubber circuit is provided for switching inductive loads such as solenoids, valves and contactor coils.
The fault output relay is energized during normal operation. When a monitored fault is detected, the relay is de-energized. Loss of the EM-M82A supply voltage therefore also produces a fault indication in the external monitoring system.
The alarm operates with an approximately one-second delay and resets automatically after the fault condition has been removed.
The load line is protected by a self-resetting 1.8 A PTC device. The unit also includes protection against voltage transients on the load line and reverse polarity at the supply input.
The control connection can normally share the supply reference. If required, the control connection can be separated from the supply circuit to provide isolation between the control and load-side circuitry.
| Supply voltage | 18–35 VDC |
|---|---|
| Overvoltage limit | 40 VDC |
| Idle current | 30 mA |
| Recommended load impedance | 15–300 Ω, depending on selected range |
| Load current, continuous | Max. 1.5 A |
| Line protection | 1.8 A self-resetting PTC |
| Sense current | 3.3 mA or 10 mA |
| Sense resistor | 1 Ω or 0.33 Ω |
| Control input resistance | 1 kΩ (pins 1–2) |
| Control input, relay energized | 18–35 VDC |
| Control input, relay released | 0–3 V |
| Impedance range 1 | 50–300 Ω, Rs = 1 Ω, Is = 3.3 mA |
| Impedance range 2 | 15–100 Ω, Rs = 0.33 Ω, Is = 10 mA |
| Fault threshold | Load resistance change below −50% or above +100% |
| Alarm delay | 1 s |
| Alarm reset | Automatic after the fault condition is removed |
| Alarm relay contact rating | 1 A at 32 VDC |
| Isolation voltage | 500 V when the control connection is separated |
Ordering larger quantities +100pcs.
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