GRMU — SF6 gas-insulated RMU monoblock 17.5 and 24 kV
GRMU is an SF6 ring main unit monoblock for 17.5 and 24 kV cable networks with LBS, vacuum circuit breaker and fuse modules. Withstand current 21 kA for 3 s or 16 kA for 1 s, local control or via SCADA.
- Rated voltage
- 17.5 and 24 kV
- Modules
- LBS, vacuum circuit breaker or fuse switch
- Short-time withstand current
- 21 kA 3 s (17.5 kV); 16 kA 1 s (24 kV)
- Making capacity
- 54.6 / 40 kA
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
GRMU (SF6 Gas Ring Main Unit) is installed in underground distribution networks of the 17.5 and 24 kV classes. The monoblock is combined from load break switch (LBS) and vacuum circuit breaker (CB) or fuse switch modules, and the composition is defined by the customer. The 24 kV model appeared in 2011 and was tested at KERI, the 17.5 kV model was developed in 2014–2015 and tested at CESI and KERI. Deliveries include large batches of 1000 RMUs for the network company PEDEE (Syria).
The internal parts are fully insulated with SF6 and enclosed in a stainless steel housing. Rated SF6 pressure is 0.14 and 0.13 MPa, minimum 0.11 and 0.10 MPa, and the leakage rate is below 0.1 % over 30 years. A rupture disc protects the housing when the gas pressure rises. The circuit breaker with vacuum interrupters has a charged spring drive, while the load break switch and the fuse switch use a toggle spring drive. The mechanism has few parts, so it lasts long and costs less to operate.
The main switch and the earthing switch are separate and mutually interlocked. During maintenance double protection applies, the earthing switch and the disconnector. Each circuit has a voltage indicator, the contact position is visible on the mimic diagram, and cables are connected with T-type plug-in connectors.
Frequency is 50/60 Hz. Short-time withstand current is 21 kA for 3 s for 17.5 kV and 16 kA for 1 s for 24 kV, making capacity 54.6 and 40 kA. The LBS module breaks a cable charging current of 10 / 40 A, the circuit breaker module 31.5 / 40 A. Service life is 2000 operations. Control is manual and automatic, local or remote via SCADA.
The manual version has the self-powered relay ETR20H, the motorized one the multi-circuit relay ETR304/306 with measurement, monitoring, recording and communication. CESI and KERI carried out the type tests to IEC 62271-100, 102, 103 and 200. GRMU is used in 10–20 kV cable distribution networks, at transformer substations and in loop schemes with automatic sectionalizing.
Technical specifications
| Rated voltage | 17.5 and 24 kV |
|---|---|
| Modules | LBS, vacuum circuit breaker or fuse switch |
| Short-time withstand current | 21 kA 3 s (17.5 kV); 16 kA 1 s (24 kV) |
| Making capacity | 54.6 / 40 kA |
| Interruption | cable charging current 10/40 A (LBS); 31.5/40 A (CB) |
| SF6 pressure | 0.14 / 0.13 MPa rated; 0.11 / 0.10 MPa min. |
| Leakage | below 0.1 % over 30 years |
| Service life | 2000 operations |
| Control | ETR20H or ETR304/306 |
| Standards | IEC 62271-1, -100, -102, -103, -200 |
Request a price and lead time
GRMU — SF6 gas-insulated RMU monoblock 17.5 and 24 kV. We reply within one business day.
Or email sales@usk.ua or call 044 339-50-20.
Customs codes
| UKTZED (Ukraine) | 8537 20 91 00 |
|---|---|
| HS, 6 digits | 8537 20 |
| CN (EU) | 8537 20 91 |
| HTSUS (USA) | 8537 20 00 00 |
| China customs tariff | 8537 20 90 00 |
Codes are for reference: the final code is determined at declaration for the specific model.
Questions and answers
What is the SF6 pressure in GRMU?
Rated SF6 pressure is 0.14 MPa for 17.5 kV and 0.13 MPa for 24 kV, minimum 0.11 and 0.10 MPa. Leakage is below 0.1 % over 30 years.
What withstand currents does the monoblock have?
The 17.5 kV model withstands 21 kA for 3 s, the 24 kV model 16 kA for 1 s. Making capacity is 54.6 and 40 kA.
To which standards was GRMU tested?
CESI and KERI carried out the type tests to IEC 62271-100, 102, 103 and 200. Service life of the monoblock is 2000 operations.
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