Quotation are invited for Supply of 1000KVA Mini Substation 6.6/0.525KV Dry Type Bulyanhulu Gold Mine (the Company), a fully owned subsidiary of Twiga Minerals Corporation, which is ultimately owned by Barrick Gold Corporation and the Government of the United Republic of Tanzania requests the submission of Quotes from reputable, experienced, certified, and qualified parties to provide the following: Material types and specifications: Apparent Power = 1000kVA Input voltage: 6600 VAC Output voltage: 525 VAC Dyn Transformer Configuration 3 Phase Input and Output Frequency = 50 Hz Impedance Z% = 5.5 The mini-substation transformers shall be suitable for continuous use at 100% of nameplate rating under the following conditions: Altitude of 1250 A.M.S.L Protection against exposure to vermin, dust, and damp depredations. Note that equipment shall be treated with corrosive protection against elements. Due to certain areas where the mini substation will be situated, anti-condensation heaters shall be required to prevent moisture build up within the mini substation. Anti-condensation heaters shall have a temperature control device. All doors shall be fitted with closed cell rubber sealing gaskets of 10 mm minimum thickness compressible to 7 mm on closing of the door. Where 3-point locking is employed, the bolt shall be manufactured from 16mm round bar. Transformers shall be of robust manufacture adequately designed and manufactured to withstand electrical fault forces and normal mechanical forces experienced in transport, installation, operation, and removal. Particular attention shall be paid to all core clamping arrangements. The minimum plate thickness to be used for any purpose (tank, cable box, cover, etc.) shall be 5mm. The mini sub enclosure shall be positively weatherproof to IP 54 enclosure class with all doors closed and covers in position. Enclosure classification shall be IP2x with LV and HV compartment doors open. The relative humidity range of 30 87% The temperature ranges 20 80 degrees Celsius Input Voltage side should have a Ring Main Unit (RMU NE-IBI) switchgear. Current rating of switchgear feeders should not be less than 12kV 25kA for 1sec, 630Amp rated. Each RMU switchgear shall have a voltage presences indication and SF6 Pressure gauge on it. RMU center feed/switchgear (B) should be equipped with a protection relay VIP 410. All standard equipment shall apply to the RMU. RMU should have distance pendant or standoff pendant for safe switching capabilities. Mini Substation should have an external box (DB) of a rating of IP65, containing the following items. Easergy PS 100 24VDC Battery Charger The output voltage of the Easergy PS 100 units 24VDC, this shall be the units control voltage. One 12VDC Battery of not less than a 24Ah, prefer 30Ah. Battery Charger Input Supply of 230VAC, Isolation breaker to be used to isolate input voltage. Battery Charger shall be fed from the L.V side with step down transformer 525/230VAC Step down transformer shall be isolated via a double pole circuit breaker. The output voltage of the battery charger (PS 100) will supply or drive the following equipment. Protection Relay of the switchgear Charging up of the RMUs B feeders Motor Mechanism. All other protection devices related to the Mini Substation, including ELSEC. Opening and closing of the switchgear breakers. L.V breakers Micro logics 2.0A on the secondary side of mini-Substation. Transformer temperature trip output to trip the RMUs B breaker switchgear of the mini substation. Temperature Alarm, Aux. control voltage healthy Indication to pilot lights will be visible on the L.V side and labeled. No fuses or fuse holders of any auxiliary supply circuit shall be used. Only circuit breakers. All components and wiring to be labelled and wiring diagram to be fixed within the auxiliary terminal box and a soft copy (.dwg and .pdf to be supplied to Barrick). Output Voltage side should have a three 3-phase, 3 pole Compact NS1250 N molded case Circuit Breaker with adjustable current setting protection relay Micrologic 2.0A. 525VAC Output Voltage sides supply to the molded case circuit breaker phases should be of a bus bar and no single core leads/tails. L.V busbars rated to carry a current carrying capacity of a 2500Amps with a short circuit rating greater or equal to 25KA, all bus bars shall be insulated per phase, and the heat shrink insulation shall be of the standard phase colors. L.V Bus bar phase arrangement after the NSX 1250 N Circuit breaker must be arranged so that I am able to connect 3x cores of 3x 185mm/sq cables lugs to a busbar phase. On the L.V. bus bars, there should be x1 meter C.T per phase before the molded circuit breaker; C.T.s must be connected to their separate analogue Amp. Meters. So that all three phase currents can be seen on the L.V. side before the molded case circuit breakers. This will include phase voltages to be viewed by x1 voltmeter with a selector switch to swing between phase voltages. Molded case Circuit Breaker must have adjustable trip settings. (Overcurrent, short circuit, and earth fault) Molded case Circuit Breaker must be able to withstand a short circuit rating greater or equal than 25kA. Mini Substation should be of a cast resin dry type Transformer with per phase transformer core temperature motoring units, visible at the L.V side of the Mini substation, these indicators should have an alarm and trip axillary contacts available. Type of cooling AF (Air Forced) if this would be possible, otherwise AN (Air Natural) with sufficient flow of air. Mini Substations transformer should have an off-load TAP (De-energized Tap Changer DETC) changer available. Tapping of the transformer must be on the high voltage winding of the transformer. Tapping range will be +5% and -5% of nominal voltage with a total of 5 tap settings of 2.5% increments. Dry type transformer should have a Temperature gauge indication with alarm and trip axillary contacts available. Mini Substation should have a NER available on the secondary star L.V side. NER resistors should have a total resistance of 30.1 Ohms and should have a Wattage rating of 3.03kW with a C.T of 10/1 ration, 10p10, 7.5VA, monitoring the neutral line to the resistors. Secondary side of the 10/1 C.T should be wired to a type of ELSEC unit. ELSEC units auxiliary output should trip the incoming feeder breaker. Mini Substation should have more than three or equal amount of earth studs available. All moving parts, like doors, shall be earthed. 3-year warranty shall apply to the mini substation. Every quotation submitted must be supplied with a GA and control circuit schematics of the protection relay and the rest of operating circuits. Key documents: Clear and detailed Quotation (Preferred incoterms 2020 DDP, FFT Mbagala Warehouse Dar es salaam) Company registration documents i.e. Certificate of incorporation, business license, TIN, VRN, Tax Clearance Certificate etc. BRELA detailed search document indicating Tanzanian ownership percentage to determine classification as an Indigenous Tanzanian Company as per the Local Content Regulation, 2018. Applicable certification, accreditation, affiliated registrations, and letter of dealership as required. Approved Local Content Plan or acknowledgement of submission from the Mining Commissioner. Full General Arrangement (GA) + Single Line (SLD) drawing to be submitted/supplied with every quotation for approval. Tender Link : https://tenders.ajirazetu.tz/supply-of-1000kva-mini-substation-6-6-0-525kv-dry-type/
