The signal list is the table that defines every data point the substation exchanges with the local SCADA and the control center: status, alarms, controls, measurands and counters, with their source, name, protocol address and handling. It is the basis of the gateway, the HMI screens and the point-to-point tests, and a mistake in it is paid for in rework during commissioning.
What the signal list is
The signal list, also called the point list or SCADA signal database, is the table that describes every data point the substation produces or receives. Each row is a signal; each column, an attribute needed by the gateway, the local SCADA, the control center and whoever tests it.
It is the document that joins three worlds: the protection and control design, which knows which signals exist; the IEDs, which produce them; and the control center, which receives them with its own protocol and addresses. That is why an error in the list spreads everywhere.
What signal types it contains
| Type | What it is | Examples |
|---|---|---|
| Double point | Position with two contacts: open, closed, intermediate or invalid | Breakers, disconnect switches, grounding switches |
| Single point | One contact or one bit | Alarms, trips, lockout relay, local-remote selector |
| Control | Command from the SCADA or the control center | Open, close, tap raise and lower, enable reclosing |
| Measurand | Analog value | Current, voltage, active and reactive power, frequency, temperature |
| Counter | Accumulated value | Energy, number of operations |
| Setpoint | Value sent to a device | Voltage reference, power limits in generating plants |
What columns it has
- Bay and equipment of origin.
- Description, clear and identical on every screen.
- Technical source: the IED and the data path (for example, the IEC 61850 logical node) or the hardwired input.
- Type and, for measurands, scale, unit and deadband.
- Protocol address toward each destination: common address and information object address in IEC 104, index in DNP3.
- With or without a time tag.
- Interrogation class or group, and whether it is sent spontaneously.
- Control model: direct or select before operate, and associated interlocks.
- Severity of the alarm and the group it belongs to.
- Destinations: local SCADA, control center, both.
- Test status: date and result of the point-to-point test.
How points are named
What works is a single convention for the whole project: substation, voltage level, bay, equipment and signal, in that order, with fixed abbreviations. What does not work is each IED vendor or each integrator using its own. When the substation is expanded years later, a clear convention is what lets a bay be added without renumbering everything.
What to group
The control center does not need every internal alarm from every relay. It usually receives:
- Positions and trips of each bay, ungrouped.
- Alarms grouped by bay and severity, for example one urgent and one non-urgent alarm per bay.
- The measurands the operator requires for system monitoring.
- The communication status of each IED.
The full detail stays in the local SCADA and in the IED event records, where maintenance staff look it up.
Relation to the control center
Each control center has its own list format and its own rules for addresses and types. Generating plants and transmission substations are usually required to be monitored in real time by the system operator, with the signals and measurements set by the local grid code and the utility’s requirements; in distribution, the distribution utility defines its own. Renewable plants may also have their own monitoring requirements: see SCADA and PMU monitoring for renewable plants.
The agreed list is taken to the gateway, which translates IEC 61850 data into the control center protocol, normally IEC 60870-5-104 or DNP3.
- 01DesignSignals per bay from the protection and control schemes
- 02AgreementAddresses, types and groupings with the control center
- 03ConfigurationIEDs, gateway and screens from the same list
- 04Point-to-point testsEach signal from its source to each destination
- 05HandoverFinal list with the result of each test
Mistakes that cause months of rework
- Agreeing the list with the control center at the end, when the gateway is already configured.
- Several live versions of the list without change control: each party works from a different one.
- Double points mapped as single points, which hide the intermediate or invalid position.
- Measurands without a defined scale or deadband, which arrive multiplied by a thousand or saturate the link.
- Controls without a defined control model, which the IED rejects.
- Test or simulation signals reaching the control center as real.
- Testing only from the gateway and not from the yard equipment: the signal exists in the database, but the wiring or the IED mapping is wrong.
How it is tested
Point-to-point tests follow each signal from its real source, the breaker contact or the injection into the relay, to each destination, and are recorded in the same list. The description, address, type and time tag are checked and, for controls, the select, the execute and the rejection by interlock. They are part of the FAT and SAT.
Your signal list with Tiza Group
We load and change the logic, interlocks and signals remotely through our remote relay and controller configuration service, without waiting for a site visit. We build the signal list from the protection and control schemes, agree it with the control center and use it to configure the IEDs, gateway and screens, as part of our SCADA and gateway integration service, in medium-, high- and extra-high-voltage substations and industry. The engineering of the list is done remotely, for projects worldwide; on-site testing is done in Colombia, or elsewhere on request. Write to us with the control center your substation must report to.
Related guides
- Substation communications by voltage level: MV, HV, EHV
- IEC 61850 to the control center: TR 61850-90-2
- Configuration management: settings and SCD versions
References
- IEC 60870-5-104: telecontrol over TCP/IP, data types and causes of transmission.
- IEEE 1815 (DNP3).
- IEC TR 61850-90-2:2016: use of IEC 61850 between substations and control centers.
- IEC 61850-7-4: logical node classes.
Frequently asked questions
Who defines a substation signal list?
Several parties build it: the protection and control design defines which signals each bay produces; the control center or grid operator defines what it wants to receive, with which addresses and types; and the integrator takes it into the gateway and the screens. There must be a single governing version, under change control.
What is the difference between the local SCADA list and the control center list?
The local SCADA list is usually broader: it includes internal IED alarms, station service supervision and diagnostics. The control center list is an agreed subset, with grouped signals and addresses set by the operator.
Why are alarms grouped instead of sending them all?
Because the control center operator needs to know which bay has a problem and how serious it is, not to read dozens of internal alarms from each relay. They are grouped by bay and severity, and the detail remains available in the local SCADA and in the IED records.