Clocks in substations delivering NTP and IRIG-B to substation automation and other systems are generally simple yet robust devices. They use GPS and other GNSS as their timing source with little or no holdover should these signals be lost.
Digital substations really change the game for timing. They require a timing accuracy <1µs for the process bus & protection systems to operate effectively in accordance with IEC-61850-5. Also, the importance of Network Security in these Critical Systems means your substation may be just a part of a timing network supported from your Core Network. This scenario may include using PTP (Precision Time Protocol) to move time and timing across your network.
GridTime 3000 (GT3k) is the first product from the Tekron stable since their acquisition by Microchip and addresses these requirements head on.
Power, GNSS and Holdover
The GT3k can be configured with single or dual power – Low Voltage (40-110 VDC) and High Voltage (120-240 VDC, 100-240 VAC). These are independent power supplies and so it is possible to configure with one Low and one High Voltage.
GNSS is a single inout at launch, with a plan to release a dual GNSS model. Current GNSS is multi-constellation L1/L2 with the roadmap including L5 multi-band. Holdover is provided by VCTCXO, OCXO or Rubidium.
Input / Output Ports for GridTime 3000
The GT3k has a generous array of I/Os available – these are enabled via software license; meaning the hardware decision on I/O Modules no longer applies and these licenses (a one-off purchase not a recurring license) can be enabled anytime during the GT3k’s life (subject to support status – see below).
- Ethernet – 2x RJ45 1GbE, 6x SFP 1GbE, 2x SFP+ 10GbE
- Two RJ48 for T1/E1/J1 Output
And Programmable Ports:
- BNC – 2x TTL or Frequency Output, 4x TTL or AM IRIG-B Output, 2x TTL Input/Output
- Two ST Fibre (62.5/125 µm) multi-mode
- One 2-pin HV MOSFET 300V 1A
- One RS 232, one RS 422
GridTime 3000 Protocols
As a next generation device, the GT3k has wide PTP protocol support, as well as support for PRP. Up to two port pairs can use PRP IEC 62439-3 (2016), with fast failover slave and support for PTP Default and Power Profiles
PTP protocols include:
- P2P/E2E delay; 1-Step/2-Step delay
- Power Profiles C37.238:2011, C37.238:2017 and IEEE 61850-9-3 Power Utility Profile
- Telecom Profiles ITU G.8265.1 and G.8275.1
In addition, the GT3k supports NTP/SNTP Stratum 1 – Multicast & Broadcast, and supports SNMP V1, V2C & V3 in addition to alarm relays and Syslog.
Warranty and Support
The GridTime 3000 is a paradigm shift in timing solutions for Power and Utilities. This is reflected in the Warranty and Support structure.
The legacy Tekron solutions offered a full ten-year return to base warranty. This is in line with the general situation across the Power and Utilities sector.
GT3k does not follow this model, instead offering a three-year warranty. This is still the longest in the Microchip timing family with options to purchase upgrades to five or ten years at purchase.
The real shift brings the GridTime 3000 into the same software-based world of the Microchip TimeProvider 4100 and SyncServer products. To receive updates and upgrades, including bug fixes and security updates, GridTime 3000 Service and Maintenance must be in place. Service and Maintenance is also required if you wish to add functionality to your GT3k (for example enabling the SFP+ ports).
This brings the GridTime 3000 in line with the telecom and enterprise sectors. It also reflects this shift from standalone commodity clocks at the network edge to the GT3k enabling a real whole network approach to network timing and security.
We are waiting to fully evaluate our GridTime device, but it is certainly placed to be the substation clock solution for the digital substation. It offers an impressive array of ports for PTP input and output while continuing the support legacy timing protocols. These protocols are used by SCADA and other systems still vital to the operation of the substation.
Using Telecom Profile PTP from the core network offers the prospect of an antenna-free substation meeting the microsecond requirements of the digital substation. I hold out hope that Microchip’s High Performance Boundary Clock finds its way to the GT3k. A substation clock with sub 100ns to UTC opens a real opportunity to build whole distribution networks within a substation for digital and legacy applications with no antenna in sight.
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