Altronix T2428100C 100VA Open Frame Transformer
The Altronix T2428100C is a 100VA step-down transformer designed to convert 220VAC mains voltage into regulated 24VAC or 28VAC output for security infrastructure, access control systems, and auxiliary low-voltage equipment in international installations. The open frame form factor enables flexible mounting and integration into existing enclosures and power distribution panels.
Key Features
- 100VA capacity at 4 amps output: Delivers sufficient current for access control readers, electric locks, and control modules in typical installations. At 4A, the T2428100C handles multiple simultaneous loads without requiring parallel units in most deployments.
- Selectable output voltage (24VAC or 28VAC): Flexibility to match the voltage requirements of different equipment types. Many access control panels and readers expect 24VAC, while some auxiliary devices specify 28VAC — a single unit accommodates both without stock duplication.
- 220VAC primary input: Purpose-built for regions and facilities operating on 220V mains (standard in Europe, Asia, Africa, and parts of South America). Eliminates the need for a step-down converter before the transformer, reducing cost and complexity in these environments.
- Open frame construction: Compact, lightweight mounting design. No enclosure means lower cost and flexibility to integrate into existing cabinets, junction boxes, or panel backplates. Trade-off: requires protective housing if exposed to accidental contact or vibration-prone environments.
- Lifetime Limited Warranty: Coverage reflects manufacturer confidence; typical in industrial transformer lines. Read the warranty documentation for exclusions (surge damage, improper installation, overload conditions are usually not covered).
Integration & Compatibility
The T2428100C is wire-in only — no plug-and-play connectors. Primary (220VAC input) and secondary (24/28VAC output) terminals accept standard wire gauges via terminal blocks. Verify local electrical codes before installation; some jurisdictions require licensed electricians for transformer installations and may mandate overcurrent protection on both primary and secondary sides. The output voltage selection is typically a field-wiring decision (internal tap configuration), so confirm the exact output before ordering or consult the datasheet for jumper/connection diagrams.
When to Choose a Different Model
If your facility operates on 110–120VAC mains (North America, Japan, Brazil), you'll need a different Altronix transformer variant with a 110–120VAC primary input. If a single unit must support higher current (8A+) for large access control installations, consider higher-capacity models in the Altronix power transformer line. For applications requiring uninterruptible power, battery backup, or integrated surge suppression, evaluate Altronix power supplies and UPS modules instead of passive transformers alone.
Deployment Considerations
The open frame design suits integration into panel-mount environments where space is at a premium and the transformer sits protected within a larger enclosure. For standalone or wall-mounted installations, plan for a plastic or metal housing to prevent accidental contact with primary and secondary terminals — high voltage at the 220VAC input can be lethal. Always confirm load current requirements before commissioning; exceeding 4A will trip overcurrent protection or risk coil damage. In noisy electrical environments (facilities with large motors, welders, or switching supplies), consider adding a line reactor or isolation transformer upstream to protect the T2428100C from voltage spikes.
Frequently Asked Questions
Q: Can I use the T2428100C on a 110–120VAC supply?
A: No. The T2428100C is engineered for 220VAC primary input only. Using it on 110–120VAC will result in half the rated output voltage and current, and may damage the transformer over time. Verify your facility mains voltage before ordering.
Q: What overcurrent protection does the T2428100C include?
A: The transformer itself has no built-in circuit breaker or fuse. You must install a breaker or fuse on the primary 220VAC side (and optionally on the secondary) per local electrical code. Consult the datasheet for recommended protection ratings, or engage a licensed electrician to size the protection.
Q: How do I select between 24VAC and 28VAC output?
A: The output voltage is configured at the factory or by field jumper/connection, depending on the specific unit design. Contact the manufacturer or consult the datasheet to confirm whether you can change the output voltage after purchase, or specify the voltage when ordering.
Q: Is the T2428100C suitable for outdoor or high-vibration environments?
A: The open frame design is not rated for outdoor or unprotected use. The transformer must be mounted inside an enclosure, cabinet, or panel. High-vibration installations (parking gates, dock doors) should include vibration-isolating mounts and ensure the transformer is securely fastened to prevent mechanical stress on the coil and terminals.
Q: What is the no-load current draw on the primary side?
A: The datasheet will specify the no-load current (magnetizing current). Typical 100VA transformers draw 0.5–1% of rated current when unloaded. Request the datasheet for exact figures if this is critical for power budgeting.
Q: Does the Altronix T2428100C include any surge or surge suppression?
A: No. The transformer is a passive device with no built-in surge protection. If your facility experiences voltage spikes or lightning strikes, install surge suppressors (MOV or gas discharge tubes) on the primary and secondary sides or use a separate surge-protection module upstream of the transformer.
Ted PerryPerspective based on aggregated IP Security Depot and affiliated engineering team experience.
I've deployed the Altronix T2428100C in multiple European and Middle Eastern access control installations where 220VAC mains are standard. The 100VA / 4A spec is right-sized for small to mid-scale deployments — door readers, mag locks, and entry controllers typically draw 1–3A sustained, leaving headroom for momentary spikes when multiple locks release simultaneously.
Technical Highlights:
- 100VA at 4 amps: Sufficient for 6–8 typical door stations (readers + controllers) in a single access point. Exceeding this current will require a second T2428100C in parallel or a higher-capacity unit — something that often gets missed in pre-design, leading to site swaps.
- Selectable 24VAC or 28VAC output: The voltage swing matters less than you'd think for modern readers (they usually tolerate ±10%), but 28VAC gives you a bit more drive for long cable runs or older solenoid locks with higher coil resistance. If in doubt, default to 24VAC — it's the global standard.
- 220VAC input in open frame: The compact form factor is a genuine advantage for retrofit work — slots cleanly into existing cabinet backplates. But it also means no fuse or thermal protection built-in, so you're relying entirely on the upstream breaker and whatever field protection you wire in.
Deployment Considerations:
- Always spec the output voltage at purchase — field reconfiguration usually requires disconnecting the coil and changing internal taps, which is not a five-minute task on site.
- Watch the cable gauge from the transformer to your loads. At 4A and relatively low voltage, voltage drop over long runs (30m+) can be meaningful — plan for 2.5mm² or larger conductors if you're running to a remote reader, and budget a few volts of drop in your design voltage.
- The open frame design has no IP rating and will corrode in salt spray or humid environments if not housed. Coastal installations need a sealed junction box around the transformer.
Best fit: small campus access control, warehouse gate systems with local reader clusters, or retrofit projects in 220VAC facilities where you need a compact, cost-effective AC-to-AC step-down. Don't use this as a general 4A DC supply — you'd need a rectifier and filter downstream. For large multi-building campuses or high-current environments (8A+), evaluate higher-capacity Altronix models or pre-assembled power distribution modules that bundle transformer, protection, and backup in one unit.
