LTB and HPL are the families of SF6 live tank circuit breakers developed by ABB and now made by Hitachi Energy. The EDF covers up to 72.5 kV, the LTB D from 72.5 to 170 kV, the LTB E up to 800 kV and the HPL B up to 1100 kV. They are operated with spring mechanisms, which in the installed base appear under names such as BLK, BLG and FSA depending on the generation and the voltage.
What it is and where it is used
LTB and HPL are the families of SF6 live tank circuit breakers developed by ABB and now published by Hitachi Energy. The ABB LTB 145 is identified mainly by its designation LTB 145D1/B. In the same line are the EDF, for voltages up to 72.5 kV, and the HPL, for high and extra-high voltage. In a live tank breaker the interrupting chamber sits at line potential on an insulating column; see high-voltage live tank circuit breaker.
They are installed in transmission and distribution substations, in line, transformer, reactor and capacitor bank bays, and in power plant and heavy industry substations, at high and extra-high voltage.
Variants: EDF, LTB D, LTB E and HPL B
| Model | Voltage according to Hitachi Energy | Main difference |
|---|---|---|
| EDF | Up to 72.5 kV | Up to 31.5 kA |
| LTB D (for example, LTB 145D1/B) | 72.5 to 170 kV | Up to 3150 A and 40 kA; also as a disconnecting circuit breaker |
| LTB E | Up to 800 kV | Up to 63 kA at 420 kV and 50 kA at 800 kV |
| HPL B | 170 to 1100 kV | Up to 80 kA and 5000 A; up to 63 kA without grading capacitors |
| EconiQ (LTA) | High voltage | Hitachi Energy line without SF6 |
| EDT | Depending on version | Live tank with integrated current transformer |
Hitachi Energy also offers some versions as a disconnecting circuit breaker, which integrates the disconnecting function. The voltage, current, breaking capacity and mechanism of each unit are read from the nameplate.
Main characteristics
- SF6 interruption with self-blast (puffer) chambers; see interrupting chamber.
- Spring mechanisms chosen according to voltage and breaking capacity. In the installed base they appear under names such as BLK, BLG, MSD and FSA; the BLG, for example, has two independent trip coils. See circuit breaker operating mechanism.
- Three-pole or single-pole operation: at extra-high voltage a mechanism per pole is usual, for single-pole reclosing and controlled switching.
- Grading capacitors on HPL units with several chambers per pole, depending on the version; see extra-high-voltage circuit breaker.
Communications and integration
The circuit breaker does not communicate by itself: position, spring charged, SF6 density and cabinet alarms reach the relay or the bay controller through auxiliary contacts, and from there SCADA over IEC 61850 or DNP3. With a controlled switching device, operation is carried out at the optimum point on the wave. See circuit breaker auxiliary contacts and circuit breaker control cabinet.
Frequently asked technical questions
- Where is the LTB 145 D1/B manual? The manual comes with each unit and depends on the mechanism and the accessories; Hitachi Energy also publishes brochures and buyer’s guides.
- Low SF6 density alarm: check the density monitor, the connections and the temperature before refilling; a leak is located before gas is replenished.
- Spring that does not charge: it is usually the supply or the motor protection, the limit switch or the motor contactor.
- Timing out of range: confirmed with the operating time test and, if needed, with the contact travel and speed test.
- Pole discrepancy in single-pole operation: the pole discrepancy logic opens all three poles if one does not follow the others.
Data from the buyer’s guide and the product pages
The following data come from the live tank circuit breaker buyer’s guide published by ABB and from the current Hitachi Energy pages for the LTB D and HPL B. Older buyer’s guides may differ from the current version; the values for your circuit breaker are on the nameplate.
| Family | Voltage | Maximum current | Maximum breaking current | Mechanism according to the guide |
|---|---|---|---|---|
| LTB D1/B | 72.5 to 170 kV | 3,150 A | 40 kA | BLK (operation per pole), FSA1 and MSD |
| LTB E1 | 72.5 to 245 kV | 4,000 A | 50 kA | BLG (three-pole) and MSD |
| LTB E2 | 362 to 550 kV | 4,000 A | 50 kA | BLG (operation per pole) and MSD |
| LTB E4 | 800 kV | 4,000 A | 50 kA | BLG (operation per pole) |
| HPL B (current page) | 170 to 1,100 kV | 5,000 A | 80 kA | not stated on the page |
The guide describes the LTB as a self-blast (“Auto-Puffer”) SF6 circuit breaker, with spring stored-energy mechanisms (BLK, BLG, MSD and FSA1). In the designation LTB xxxEy, the last digit is the number of interrupting chambers in series per pole: one, two or four. The normal ambient temperature range is −30 to +40 °C, and units can be supplied for −60 °C or +70 °C. The exact assignment of each mechanism to each version is not unambiguous in the guide; consult the mechanism nameplate.
HPL B
Hitachi Energy presents the HPL B up to 1,100 kV as a circuit breaker and up to 550 kV as a disconnecting circuit breaker. It groups it into three series: HPL 170-300B1, HPL 420-550B2 and HPL 800-1100B4. It states 5,000 A continuous current and 80 kA breaking current, with 63 kA when it has no grading capacitors; with only two interrupting chambers it reaches 80 kA. It declares mechanical class M2 with 10,000 operations, a service life of more than 30 years and high seismic withstand. It is designed and tested according to IEC and ANSI, and the page also cites tests to the national standards GOST, DL and DIN. Applications listed: lines, transformers, reactors, capacitor banks and harmonic filters, at altitude, in seismic zones and at extreme temperatures.
Disconnecting circuit breaker
The disconnecting circuit breaker (DCB) integrates the disconnecting function into the circuit breaker itself, so the bay disconnector is omitted. The specific standard is IEC 62271-108, which covers AC disconnecting circuit breakers for systems of 72.5 kV and above and refers to the requirements of IEC 62271-100 and 62271-102; the current edition is from 2020. Because in the open position the circuit breaker also performs the disconnector function, the position signal and the bay interlocks must be consistent with that dual function. The LTB D is also offered as a DCB.
Controlled switching
Because the LTB and HPL are used on reactors, capacitor banks and transformers, it is common to complement them with a controlled switching device. The effect depends on the circuit breaker timings remaining stable with temperature, control voltage and time since the last operation, so those three factors are recorded during testing. CIGRE has published controlled switching guides and, in 2019, Technical Brochure 757 on the commissioning and operation of controlled switching projects; it is the current reference for whoever specifies or receives one of these controllers.
Points of attention
- Cold climate. SF6 density falls with temperature; at cold sites, the filling pressure and the heaters are defined with the manufacturer according to the minimum temperature. A low-density alarm in winter is not the same as a leak; see SF6 density monitor.
- Polymer insulators. Hitachi Energy offers them as an option for greater reliability and availability; their inspection differs from that of porcelain.
- Operation per pole. With one mechanism per pole there is pole discrepancy logic and independent timing per phase; the operating time test is interpreted phase by phase.
- SF6-free circuit breakers. Hitachi Energy has a high-voltage line without SF6 (EconiQ); its maintenance and gas values are specific to it.
How we help
At Tiza Group we do not sell circuit breakers. We test and commission LTB, HPL and EDF circuit breakers and those of any brand: timing, contact resistance, travel, coils, mechanism and SF6 gas analysis, and we verify the bay control and protection circuits, in Colombia or elsewhere on request. See circuit breaker testing within testing and commissioning. If you are going to replace an old circuit breaker, we design the change under engineering design and studies. Write to us through the contact page.
Related guides
- High-voltage live tank circuit breaker
- Extra-high-voltage circuit breaker
- Circuit breaker operating mechanism
- Circuit breaker operating time test
- Contact resistance test
- SF6 density monitor
- Siemens 3AP1 FG, 3AP1 FI, 3AP2 and 3AP4 circuit breakers
References
- IEC 62271-100, alternating-current circuit-breakers for high voltage.
- IEEE C37.04, rating structure for AC high-voltage circuit breakers.
- Hitachi Energy, product pages for EDF, LTB D, LTB E, HPL B, EconiQ and EDT, and the air-insulated switchgear portfolio.
- Patent application on operating mechanisms for live tank circuit breakers (BLK, BLG, MSD and FSA mechanisms according to the rated value).
Frequently asked questions
What does LTB 145D1/B mean?
It is the designation of an LTB live tank circuit breaker for 145 kV in the D series. LTB is the family, 145 the rated voltage in kV and D1/B identifies the design version. According to Hitachi Energy, the LTB D covers 72.5 to 170 kV with a breaking current of up to 40 kA.
Is the ABB LTB breaker now a Hitachi Energy product?
Yes. ABB's power grids business moved to Hitachi Energy, which now publishes the LTB, HPL and EDF families. On installed equipment the nameplate says ABB; documentation and spare parts are handled through Hitachi Energy.
Where can I find the manual for the ABB LTB 145D1/B?
Hitachi Energy publishes brochures and buyer's guides in its library, and supplies the installation, operation and maintenance manual with each circuit breaker. Request it with the serial number, because the mechanism and the accessories change per order.