The P139 binary inputs are optocoupled: each one activates its assigned function when it receives voltage (active high) or loses it (active low). The test consists of applying or removing voltage at each terminal and checking its state in the relay and the associated function.
How a P139 binary input works
The MiCOM P139 binary inputs use optocouplers. Each one can activate a relay function: blocking, switching command, breaker position, interlocking signal and others. That function is assigned by configuration, and the same function can be assigned to several inputs, which allows activating it from control points at different voltages. For the relay and its settings, see MiCOM P139: sheet and settings.
Four parameters that define the test
| Parameter | What it defines |
|---|---|
| Function assignment | What the input activates |
| Operating mode | Active «high» or «low», with or without filter |
| Filter | Number of sampling steps the signal must hold (step = period/20) |
| State | Reading: high, low or no function |
Active-high mode reads the presence of voltage as logic 1; active-low, its absence. The state display shows «High» if the input is energized and «Low» if not, regardless of the mode chosen. «No function» means no function is assigned.
For the relay to recognize a signal in normal operation it must last at least 20 ms. If it coincides with a general start, the manual recommends raising that time to 40 ms in unfavorable conditions. Time-critical signals, such as clock synchronization, should not be tied to the analog module’s inputs, because those have a longer reaction time.
How it is verified
With the bay out of service and following the terminal diagram:
- Confirm that the selected bay type is correct: selecting it assigns the inputs and outputs by itself.
- Check that the function assigned to each input matches the diagram.
- Apply the control voltage to each terminal and read the state in the relay; it must change from «Low» to «High» (or the reverse in low mode).
- Confirm that the associated function activates: signal, blocking or interlock as applicable.
- If the filter is used, test with a pulse shorter than the filter and confirm the relay does not recognize it.
The control voltage must be the installation’s (and different per input if the design provides for it); the relay accepts any auxiliary voltage on its inputs, within its range.
Inputs and outputs together
The same commissioning screen lets you drive the output relays for an adjustable time and verify the measuring inputs with injected values. It is the way to check the complete circuit: from the terminal to the relay, and from the relay to the output.
Common errors
- High/low mode opposite to the contact: the function activates the wrong way round.
- Wrong bay type: the inputs end up with another function.
- Signal shorter than the minimum time or the filter.
- Control voltage that does not match the input.
How we help
We test the inputs and outputs of medium-voltage relays at commissioning, point to point, and leave the record. See testing and commissioning and, for settings, the remote configuration of MiCOM relays.
Related guides
- MiCOM P139: sheet and feeder settings
- MiCOM P14x relay
- Primary and secondary injection
- Secondary injection test sets
References
- Schneider Electric, MiCOM P139, technical manual P139/ES M/Aa8: configuration and operating mode of the digital inputs; commissioning.
Frequently asked questions
How long must a signal last for the P139 to recognize it?
At least 20 ms in normal operation. If it coincides with a general start, the manual says the time should rise to 40 ms in unfavorable conditions.
What does active-high or active-low mean for a binary input?
Whether the presence of voltage (high) or its absence (low) is read as logic 1. The state shown on the display is independent of this setting.
What is the filter on a binary input for?
To suppress transient interference spikes: a change of state is recognized only if the signal holds for the number of sampling steps set in the filter parameter.