# Grafana - Show phase difference between two PMUs

**URL:** <http://discussions.gridprotectionalliance.org/t/grafana-show-phase-difference-between-two-pmus/750>\
**Category:** openHistorian\
**Created:** [August 25, 2020, 1:07pm UTC](http://discussions.gridprotectionalliance.org/t/grafana-show-phase-difference-between-two-pmus/750 "2020-08-25T13:07:43Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![OpenPMU](http://discussions.gridprotectionalliance.org/letter_avatar_proxy/v4/letter/o/9d8465/32.png) [@OpenPMU](http://discussions.gridprotectionalliance.org/u/OpenPMU)\
**Post date:** [August 25, 2020, 1:07pm UTC](http://discussions.gridprotectionalliance.org/t/grafana-show-phase-difference-between-two-pmus/750/1 "2020-08-25T13:07:43Z")

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Hello, I’m wondering if there’s a method to show the phase angle difference between two PMUs on Grafana?

I can get the two angles (PMU 1 and PMU 2) to plot on the one panel, but I don’t seem to be able to apply the Subtract function to subtract one angle from the other?

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**Author:** ![ritchiecarroll](http://discussions.gridprotectionalliance.org/user_avatar/discussions.gridprotectionalliance.org/ritchiecarroll/32/2_2.png) [@ritchiecarroll](http://discussions.gridprotectionalliance.org/u/ritchiecarroll)\
**Post date:** [September 10, 2020, 8:42pm UTC](http://discussions.gridprotectionalliance.org/t/grafana-show-phase-difference-between-two-pmus/750/2 "2020-09-10T20:42:36Z")

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Read the following steps:

> <https://github.com/GridProtectionAlliance/gsf/blob/master/Source/Documentation/GrafanaFunctions.md#series-functions>