Component Snapshot At-a-Glance

• Full Model: BGTR8HE 24491276A1004
• Part Serial No: 24491276A1004
• Alt. P/N: BGTR8HE 24491276A1005 (higher data storage variant); BGTR7HE (lower power compact version)
• Manufacturer: ALSTOM (later GE Grid Solutions, legacy power system protection platform)
• Product Series: BGTR series substation rack auxiliary power supply unit, matched to Midos draw-out relay cabinet backplane
• Hardware Type: Hot-swappable plug-in rack-mounted switching power supply module, metal shielded chassis, front panel status LED & fault alarm dry contacts
• Key Feature: Wide universal AC/DC dual input, stabilized 24VDC isolated output, N+1 redundant parallel support, full multi-stage fault protection, convection cooling (no fan wear failure risk), conformal coated PCB for corrosive substation environments
• Primary Field Use: Provide stable 24VDC auxiliary operating power to all Midos series protection relays (MCGG/MVAJ/MFAC/MCTI/MVTU/MAVS/MVTU), DCS communication boards, PT/CT signal conditioning circuits and substation SCADA alarm logic in power plant & primary distribution switchgear cubicles

Hard-Numbers: Technical Specifications

• Input Range (Universal Dual Input):AC: 110–240VAC 50/60Hz; DC: 125/250VDC station battery direct feed
• Output Rating: 24VDC stabilized isolated DC, 150W continuous rated power, max 6.25A
• Efficiency: ≥90% full load; Power Factor ≥0.95
• Parallel Redundancy: Supports N+1 hot parallel operation for non-stop protection power supply
• Built-In Protections: Overvoltage OVP, Overload OLP, Short-circuit auto-recovery, input reverse polarity blocking
• Alarm Interfaces: Volt-free dry fault contacts for AC input loss, DC overvoltage, module overheat, output overload
• Isolation Grade: 2500Vrms isolation between primary input and secondary 24V output
• Operating Temp: -20°C ~ +70°C cabinet operational; Storage -40°C ~ +85°C
• EMC Compliance: IEC 61000-6-2 (industrial immunity), IEC 61000-6-4 emission standard
• Safety Standard: IEC/EN 60950, UL 508 industrial control equipment certification
• Mounting: Standard 19-inch substation rack hot-swappable plug-in form factor
• PCB Treatment: Full conformal acrylic coating, anti-sulfur/anti-salt fog for coastal/refinery substations
• MTBF: >100,000 hours under nominal substation ambient conditions
• Physical Weight: 1.5kg fully assembled shielded module

The Real-World Problem It Solves

Discrete small DIN rail power supplies lack parallel redundancy capability; single power supply failure cuts DC power to entire bank of Midos protection relays, causing complete loss of feeder/transformer fault protection and catastrophic unplanned blackouts.Standard unisolated low-grade DC converters generate ground loop noise and switching EMI, distorting PT voltage & CT current analog signals, triggering random nuisance trips on differential and distance protection relays (MFAC/MVTU).Fan-cooled power supplies suffer fan bearing failure in dusty substation environments; BGTR8HE convection-only design eliminates moving part wear points and reduces annual maintenance workload.Separate external fault alarm relays add extra rack slots and vibration-prone wiring splices; BGTR8HE integrates dedicated fault alarm contacts to directly wire SCADA cabinet fault annunciator panels without auxiliary hardware.Low-power BGTR7HE variants cannot fully load dense Midos relay racks with 10+ draw-out protection units; BGTR8HE 150W high-output rating supports fully populated multi-feeder protection cubicles without DC bus voltage sag.Where you’ll typically find it:

• Fossil power plant generator, main transformer and boiler feeder Midos protection relay rack power feed cabinets
• Refinery primary MV switchgear multi-infeed bus differential & distance protection cubicles
• Urban distribution primary substation ring bus transformer and overhead feeder protection control panelsThis single hot-swappable rack power module delivers isolated redundant 24VDC power for full Midos relay racks, eliminates EMI interference with analog fault measurement circuits, and removes fan wear failure risks for mission-critical substation protection systems.

Hardware Architecture & Under-the-Hood Logic

This unit uses two-stage isolated switching conversion topology, primary EMI filter front-end + secondary closed-loop voltage regulation, no user programmable firmware; designed for direct plug-in to ALSTOM standard protection rack backplane power bus.

1. Universal AC/DC input stage with multi-stage LC EMI filter suppresses substation switching surge noise from grid fault transients and VFD equipment, prevents power supply distortion from polluted station auxiliary supply.
2. High-frequency isolated switching converter with full metal shielding blocks internal switching noise leakage to adjacent CT/PT signal wiring, eliminating ground loop offset in differential and voltage supervision relays.
3. Secondary closed-loop regulation circuit maintains tight ±1% 24VDC output stability across full 0–100% load range, critical to avoid Midos relay coil dropout during simultaneous multi-feeder fault DC load spikes.
4. Parallel load-sharing circuitry built-in; multiple BGTR8HE modules auto-balance output current for N+1 redundant architecture, single module failure does not drop 24V bus voltage.
5. Front panel multi-color LED status indicators: Input healthy, DC output active, overheat fault, overload alarm for rapid on-site visual troubleshooting without DCS workstation access.
6. Rear rack edge gold-plated backplane connector with slide-lock retention clips, anti-vibration design to prevent loose power contact under plant load thermal cycling; conformal coated PCB prevents corrosion in chemical/coastal substation environments.

Field Service Pitfalls: What Rookies Get Wrong

Swapping BGTR7HE Low-Power Compact Variant For 150W Unit

New technicians install BGTR7HE spare without matching model suffix. Fully populated Midos relay racks exceed BGTR7HE power rating, DC bus voltage collapses under simultaneous fault load, all protection relays dropout and lose fault detection capability.Field Rule: mandatory for racks with ≥6 Midos draw-out relays; BGTR7HE only for small single-feeder compact cubicles with ≤3 relays. Segregate BGTR7/BGTR8 spares in locked labeled storage bins.

Hot-Swap Module Without Disabling Parallel Redundancy Interlock

Apprentices pull module while N+1 parallel units active without isolating alarm wiring. Momentary DC bus dip triggers all voltage supervision MVTU relays to block distance protection, creating temporary blind fault detection window.Quick Fix: Before hot swap, disable SCADA fault alarm circuit and confirm remaining parallel module carries full rack load without voltage sag before removing faulty unit.

Routing CT/PT Analog Signal Cables Parallel To Power Output Wiring

Maintenance crews run unshielded CT/PT wiring alongside module 24VDC output cables. Switching EMI noise distorts sequence voltage and differential current readings, protection relays randomly nuisance trip during breaker switching events.Field Rule: Separate analog CT/PT signal wiring into dedicated shielded cable trays; power supply DC wiring routed in isolated cable ducts, single-point shield ground at relay rack only.

Deploying Uncoated Surplus Modules In Coastal/Refinery Corrosive Cubicles

Field crews install uncoated used units without checking PCB conformal coating. Sulfur and salt vapor corrodes PCB trace pads within 3–6 months, creating intermittent 24VDC voltage drop and random relay power loss.Field Rule: Only fully conformal coated 24491276A1004 modules allowed in chemical, coastal, offshore substations; re-coat bare PCB surplus before rack installation.

Overloading Output Bus With Extra Unregulated Auxiliary Loads

Techs add cabinet lighting, auxiliary heater loads direct to 24V output terminals. Excess load triggers permanent overload protection lockout, all Midos protection relays lose operating power.Field Rule: output exclusively reserved for protection relays & signal conditioning boards; all non-protection auxiliary loads wired to separate dedicated station DC battery feed.

Commercial Availability & Pricing Note

Please note: The listed price is for reference only and is not binding. Final pricing and terms are subject to negotiation based on current market conditions and availability.