14.6. Instantaneous Data

14.6.1. Summary

Instantaneous data provides a continuous stream of scalar metrological data as provided by the host device, with data being pushed at least once a second. Platforms MAY push data more frequently; however, data push periodicity MUST be consistent. The instantaneous data push periodicity MUST be reported in the Platform Discovery transaction.

When supported by the platform, instantaneous data is available to authorized applications without a separate activation transaction. There is no need to specifically request or activate it; applications can simply subscribe to the topic.

This API carries scalar metered quantities and remains distinct from the high-rate waveform API.

14.6.2. Profiles and Required Values

The base GEISA metered-quantities schema is capability-tolerant so it can support different device and platform architectures. A field being defined by the base schema does not make it mandatory for every platform, and applications MUST tolerate absent standardized values unless another applicable requirement or profile makes them mandatory.

Profiles define required subsets appropriate to specific device or capability classes. The GEISA AC Meter Profile defines the current minimum required scalar AC metrology baseline for implementations of that profile.

Note that this baseline is intentionally conservative for the current specification version, and GEISA expects the base profile set and profile-required metered quantities to expand in future specification versions as implementation experience and application requirements mature.

The current AC Meter Profile directly requires the phase-a and system objects. Additional phases may be required according to meter form, phase count, Platform Discovery, and conformance logic. Platforms not claiming the AC Meter Profile may expose a different applicable subset when permitted by another profile or capability model.

Scalar metered quantities remain separate from waveform frame delivery. Billing quantities use separate metered-quantities payloads and profile definitions and are not part of the instantaneous scalar profile.

14.6.3. AC Meter Profile Required Fields

The following two tables list the current AC Meter Profile required instantaneous fields. Every row shown here is required for the AC Meter Profile. Additional phase objects may also be required according to meter form, phase count, Platform Discovery, etc.

Table 14.3 Required Outer Payload and phase-a Fields

Scope	Field	Encoding / Unit	Meaning / Applicability
Outer payload	message-version	uint32 integer	Top-level message version
Outer payload	timestamp-us	uint64 UTC Unix epoch microseconds	Top-level timestamp
phase-a	message-version	uint32 integer	Phase message version
phase-a	phase	String enum PHASE_A | PHASE_B | PHASE_C | PHASE_N	Phase selector; AC Meter Profile uses PHASE_A here.
phase-a	voltage-micro-v	int64 fixed-point microvolts	Phase RMS voltage
phase-a	current-micro-a	int64 fixed-point microamps	Phase RMS current
phase-a	active-power-micro-w-sum	int64 fixed-point microwatts	Phase active power sum
phase-a	reactive-power-micro-var-sum	int64 fixed-point microvars	Phase reactive power sum
phase-a	apparent-power-micro-va-sum	int64 fixed-point microvolt-amperes	Phase apparent power sum
phase-a	power-factor	double ratio 0.0 to 1.0	Phase power factor magnitude
phase-a	current-angle-deg	double degrees	Phase current angle
phase-a	voltage-angle-deg	double degrees	Phase voltage angle
phase-a	current-thd-percent	double percent	Phase current THD
phase-a	voltage-thd-percent	double percent	Phase voltage THD
phase-a	current-tdd-percent	double percent	Phase current TDD

Table 14.4 Required System Fields

Scope	Field	Encoding / Unit	Meaning / Applicability
system	message-version	uint32 integer	System message version
system	timestamp-us	uint64 UTC Unix epoch microseconds	System timestamp
system	frequency-hz	double hertz	System frequency
system	active-power-micro-w-sum	int64 fixed-point microwatts	System active power sum
system	reactive-power-micro-var-sum	int64 fixed-point microvars	System reactive power sum
system	apparent-power-micro-va-sum-arithmetic	int64 fixed-point microvolt-amperes	System arithmetic apparent power sum; required as the profile aggregate apparent power baseline
system	power-factor-arithmetic	double ratio 0.0 to 1.0	System arithmetic power factor magnitude

14.6.4. Additional Standardized Instantaneous Quantities

The base metered-quantities schema standardizes additional instantaneous fields beyond the current AC Meter Profile baseline. These fields remain interoperable when present, but applications MUST tolerate their absence unless another applicable requirement or future profile makes them mandatory.

Additional phase objects may be present when supported by the platform and may become required according to meter form, phase count, Platform Discovery, and conformance logic even though the current AC Meter Profile directly requires only the phase-a and system objects.

Table 14.5 Additional Standardized Optional Instantaneous Fields

Scope	Field	Description	Encoding / Unit	Applicability / Notes
Outer instantaneous message	frequency-hz	Optional top-level instantaneous frequency	double hertz	Standardized by the base schema but not required by the current AC Meter Profile.
Outer instantaneous message	temperature-celsius	Optional top-level platform or meter temperature	double degrees Celsius	Standardized by the base schema but not required by the current AC Meter Profile.
Outer instantaneous message	metadata	Optional top-level measurement metadata	Object with measurement-period-s	Presence is meaningful; measurement periods describe averaging or integration windows rather than MQTT publication cadence.
Per applicable phase	current-micro-a-fundamental	Per-phase RMS current fundamental component	int64 fixed-point microamps	Standardized by the base schema but not required by the current AC Meter Profile.
Per applicable phase	voltage-micro-v-fundamental	Per-phase RMS voltage fundamental component	int64 fixed-point microvolts	Standardized by the base schema but not required by the current AC Meter Profile.
Per applicable phase	power-factor-angle-deg	Per-phase power factor angle	double degrees	Power factor values remain unsigned magnitudes; directional context comes from power values and angles rather than PF sign.
Per applicable phase	current-distortion-micro-a-rms	Per-phase distortion current RMS	int64 fixed-point microamps	Standardized by the base schema but not required by the current AC Meter Profile.
Per applicable phase	voltage-2nd-harmonic-percent	Per-phase second harmonic voltage magnitude	double percent	Percentage semantics use 0 through 100 rather than 0.0 through 1.0.
Per applicable phase	metadata	Optional per-phase measurement metadata	Object with measurement-period-s	Presence is meaningful; applies to the same per-phase structure used by applicable phase objects.
Per applicable phase	active-power-micro-w-del	Per-phase delivered active power	int64 fixed-point microwatts	Standardized by the base schema but not required by the current AC Meter Profile.
Per applicable phase	active-power-micro-w-rec	Per-phase received active power	int64 fixed-point microwatts	Standardized by the base schema but not required by the current AC Meter Profile.
Per applicable phase	active-power-micro-w-net	Per-phase net active power	int64 fixed-point microwatts	Standardized by the base schema but not required by the current AC Meter Profile.
Per applicable phase	reactive-power-micro-var-del	Per-phase delivered reactive power	int64 fixed-point microvars	Standardized by the base schema but not required by the current AC Meter Profile.
Per applicable phase	reactive-power-micro-var-rec	Per-phase received reactive power	int64 fixed-point microvars	Standardized by the base schema but not required by the current AC Meter Profile.
Per applicable phase	reactive-power-micro-var-net	Per-phase net reactive power	int64 fixed-point microvars	Standardized by the base schema but not required by the current AC Meter Profile.
System aggregate	apparent-power-micro-va-sum-vectorial	System vectorial apparent power sum	int64 fixed-point microvolt-amperes	Arithmetic and vectorial aggregate values may coexist when both are available.
System aggregate	power-factor-vectorial	System vectorial power factor magnitude	double ratio 0.0 to 1.0	Arithmetic and vectorial aggregate values may coexist when both are available.
System aggregate	reactive-power-micro-var-sum-arithmetic	System arithmetic reactive power sum	int64 fixed-point microvars	Standardized by the base schema but not required by the current AC Meter Profile.
System aggregate	power-factor-angle-arithmetic-deg	System arithmetic power factor angle	double degrees	Power factor values remain unsigned magnitudes; directional context comes from power values and angles rather than PF sign.
System aggregate	power-factor-angle-vectorial-deg	System vectorial power factor angle	double degrees	Power factor values remain unsigned magnitudes; directional context comes from power values and angles rather than PF sign.
System aggregate	metadata	Optional system measurement metadata	Object with measurement-period-s	Presence is meaningful; measurement periods describe averaging or integration windows rather than MQTT publication cadence.
System aggregate	active-power-micro-w-del	System delivered active power	int64 fixed-point microwatts	Standardized by the base schema but not required by the current AC Meter Profile.
System aggregate	active-power-micro-w-rec	System received active power	int64 fixed-point microwatts	Standardized by the base schema but not required by the current AC Meter Profile.
System aggregate	active-power-micro-w-net	System net active power	int64 fixed-point microwatts	Standardized by the base schema but not required by the current AC Meter Profile.
System aggregate	reactive-power-micro-var-del	System delivered reactive power	int64 fixed-point microvars	Standardized by the base schema but not required by the current AC Meter Profile.
System aggregate	reactive-power-micro-var-rec	System received reactive power	int64 fixed-point microvars	Standardized by the base schema but not required by the current AC Meter Profile.
System aggregate	reactive-power-micro-var-net	System net reactive power	int64 fixed-point microvars	Standardized by the base schema but not required by the current AC Meter Profile.
Auxiliary other object	neutral-current-imputed-micro-a	Imputed neutral current	int64 fixed-point microamps	Standardized by the base schema but not required by the current AC Meter Profile.
Auxiliary other object	load-side-voltage-micro-v	Load-side voltage	int64 fixed-point microvolts	Standardized by the base schema but not required by the current AC Meter Profile.
Auxiliary other object	neutral-current-micro-a	Measured neutral current	int64 fixed-point microamps	Standardized by the base schema but not required by the current AC Meter Profile.
Auxiliary other object	metadata	Optional auxiliary measurement metadata	Object with measurement-period-s	Presence is meaningful; measurement periods describe averaging or integration windows rather than MQTT publication cadence.
Harmonic scalar values	phase-a-current-harmonic-2nd-micro-a	Phase A second harmonic current magnitude	int64 fixed-point microamps	Standardized by the base schema but not required by the current AC Meter Profile.
Harmonic scalar values	phase-b-current-harmonic-2nd-micro-a	Phase B second harmonic current magnitude	int64 fixed-point microamps	Standardized by the base schema but not required by the current AC Meter Profile.
Harmonic scalar values	phase-c-current-harmonic-2nd-micro-a	Phase C second harmonic current magnitude	int64 fixed-point microamps	Standardized by the base schema but not required by the current AC Meter Profile.
Harmonic scalar values	phase-a-voltage-harmonic-2nd-micro-v	Phase A second harmonic voltage magnitude	int64 fixed-point microvolts	Standardized by the base schema but not required by the current AC Meter Profile.
Harmonic scalar values	phase-b-voltage-harmonic-2nd-micro-v	Phase B second harmonic voltage magnitude	int64 fixed-point microvolts	Standardized by the base schema but not required by the current AC Meter Profile.
Harmonic scalar values	phase-c-voltage-harmonic-2nd-micro-v	Phase C second harmonic voltage magnitude	int64 fixed-point microvolts	Standardized by the base schema but not required by the current AC Meter Profile.
Harmonic arrays	phase-a-harmonics.voltage-harmonic-micro-v	Phase A harmonic voltage magnitude array	Array of int64 fixed-point microvolts	Array index 0 represents the second harmonic; index 1 the third harmonic; and so forth.
Harmonic arrays	phase-a-harmonics.current-harmonic-micro-a	Phase A harmonic current magnitude array	Array of int64 fixed-point microamps	Array index 0 represents the second harmonic; index 1 the third harmonic; and so forth.
Harmonic arrays	phase-b-harmonics.voltage-harmonic-micro-v	Phase B harmonic voltage magnitude array	Array of int64 fixed-point microvolts	Array index 0 represents the second harmonic; index 1 the third harmonic; and so forth.
Harmonic arrays	phase-b-harmonics.current-harmonic-micro-a	Phase B harmonic current magnitude array	Array of int64 fixed-point microamps	Array index 0 represents the second harmonic; index 1 the third harmonic; and so forth.
Harmonic arrays	phase-c-harmonics.voltage-harmonic-micro-v	Phase C harmonic voltage magnitude array	Array of int64 fixed-point microvolts	Array index 0 represents the second harmonic; index 1 the third harmonic; and so forth.
Harmonic arrays	phase-c-harmonics.current-harmonic-micro-a	Phase C harmonic current magnitude array	Array of int64 fixed-point microamps	Array index 0 represents the second harmonic; index 1 the third harmonic; and so forth.
Harmonic arrays	metadata	Optional harmonic measurement metadata	Object with measurement-period-s	Presence is meaningful; measurement periods describe averaging or integration windows rather than MQTT publication cadence.

14.6.5. Value Semantics

• JSON schema and profile documents currently use hyphenated field names while the protobuf source uses an underscore naming convention

• Electrical integer values use the fixed-point micro-unit identified by the field name

• timestamp-us is UTC Unix epoch time in microseconds

• Proto3 optional presence distinguishes an absent or unsupported value from a valid zero

• Power factor is an unsigned magnitude in the range 0.0 through 1.0

• Directional and quadrant context comes from applicable active and reactive power fields and angles rather than power factor sign

• THD, TDD, and second-harmonic percentage fields use 0 through 100 percentage semantics

• Measurement metadata describes averaging or integration windows and is not the publication cadence

• Arithmetic aggregate apparent power and power factor are required by the current AC Meter Profile

• Optional vectorial aggregate values may also be published; arithmetic and vectorial values are not mutually exclusive

Note

Some jurisdictions, including Canada, may prefer or require vectorial calculations for selected aggregate metered quantities. The GEISA metered-quantities schema distinguishes arithmetic and vectorial aggregate values using separate field names where both calculation methods are defined. The current AC Meter Profile requires arithmetic aggregate apparent power and power factor as the baseline; vectorial aggregate values may also be published when supported by the platform. Applications that require vectorial aggregate values must tolerate their absence unless another applicable profile or requirement makes them mandatory.

14.6.6. MQTT Details

• QoS: 0 / Unacknowledged

• Topic: geisa/api/instantaneous/data

14.6.7. API Permissions

• Application:

  • Subscribe: geisa/api/instantaneous/data

• Platform:

  • Publish: geisa/api/instantaneous/data

14.6.8. Transaction Data

• GeisaInstantaneousQuantities

As defined in https://github.com/geisa/schemas