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The SV delay parameter, found via menu path Configuration/System, defines how long the receiver waits for the SMV frames before activating the SMVRECEIVE ALARM output. This setting also delays the local measurements of the receiver to keep them correctly time aligned. The SV delay values include sampling, processing and network delay.

SMVRECEIVE WARNING output is set TRUE if two consecutive frames are lost. ALARM output is set TRUE if three or more frames in a sequence is lost. A single loss of frame is corrected with a zero-order hold scheme, the affect on protection is considered negligible in this case and it does not activate the SMVRECEIVE WARNING or ALARM outputs.

Table 1. Protection delays and network margins for 9-2LE at 50 Hz
SV Delay setting (%)	Ethernet network margin (ms)	Protection delay (ms)
50	0,656	2,606
75	0,984	2,934
100	1,313	3,263
125	1,641	3,591
150	1,969	3,919
200	2,625	4,575
300	3,938	5,888
5000	65,625	67,575

Table 2. Protection delays and network margins for 9-2LE at 60 Hz and IEC 61869-9 at 50 Hz and 60 Hz
SV Delay setting (%)	Ethernet network margin (ms)	Protection delay (ms)
50	0,547	2,497
75	0,82	2,77
100	1,094	3,044
125	1,367	3,317
150	1,641	3,591
200	2,188	4,138
300	3,281	5,231
5000	54,688	56,638

Because SV delay impacts directly the protection speed, big values are meant for non-time critical applications, like alarming. Increasing SV delay might be necessary for high latency networks for example in case of mobile networks.

When using routable SV, there’s additional R-SV delay parameter that can be used to adjust the total network delay and therefore also the protection delay. The formula to calculate the total protection delay using R-SV delay is the following:

Where Delay_Eth is the Ethernet margin, Delay_R-SV is the configured R-SV delay and SampleDistance is the SV sample distance in milliseconds. See table below for SV sample distances.

Table 3. SV sample distances
SV Profile	SV sample distance (ms)
9-2LE at 50 Hz	0,250
9-2LE at 60 Hz	0,208
IEC 61869-9 at 50 Hz	0,208
IEC 61869-9 at 60 Hz	0,208

For example, consider the R-SV delay setting of 0,5 ms, the SV delay setting of 100% using IEC 61869-9 at 50 Hz. The total protection delay would be the following: