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ION 7650/7550: Response time from detecting a disturbance/transient to triggering a digital output

Issue
What is the response time from detecting a disturbance/transient to triggering a digital output?

Product Line
ION 7650
ION 7550

Environment
Digital Outputs
Power Quality Detection

Cause
To determine the response time of a digital output from a power quality event

Resolution
ION7550/7650 can do high-speed digital out triggering since the digital out module will update every half-cycle (i.e. 0.01s for 50Hz). Thus, when the transient module fires AnyTrig, the digital out module will respond within 0.01 seconds.

However, the actual amount of time from a sag/swell/transient on the line, to the digital output triggering is not a half-cycle. The half-cycle time represents the transient/sag/swell ION modules update rate. The actual chain of events is as follows:
1. Transient occurs during a sampling window (1/2 cycle) 
2. DSP processes transient (1/2 cycle)
3. DSP transfers data to main processor, and main processor fires ION modules (1/2 cycle)
4. Digital out changes state (1ms for solid state digital outs, 8 to 15 ms for mechanical relays)

At 50 Hz, the total time for the solid-state digital out to change state based on a transient at the start of the sampling window, is 1.5 cycles + 1ms = 31ms.
At 60 Hz, the total time for the solid-state digital out to change state based on a transient at the start of the sampling window, is 1.5 cycles + 1ms = 26ms.

The sag/swell and transient modules can both be used to trigger digital outputs in this case, as they are both high-speed modules.

You can use a Pulse Merge Module to trigger the digital out from both at once. It is also likely you will need to use a One Shot Timer to turn the digital output off again.

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