Why I Insist on GE Multilin 845 Transformer Protection Relays (and You Should Too)

I’ll Say It Upfront: The GE Multilin 845 Is Worth Every Penny

When I took over purchasing for our facility in 2022, I inherited a messy setup – separate protection relays, standalone surge protectors for AC units, and a control panel box that looked like a spaghetti factory exploded inside. The first time a lightning strike took out our distribution transformer (and all the downstream equipment), I spent three weeks chasing invoices, coordinating repairs, and explaining to my VP why we lost production time. That’s when I became a fervent believer in the GE 845 transformer protection relay – not because it’s the flashiest option, but because it solves a problem most people overlook: efficiency through integration.

Look, I know the allure of buying individual components – a cheaper relay here, a basic surge protector there. It feels budget-friendly on paper. But in my experience, that approach costs way more in hidden operational drag than any upfront saving. Here’s why.

Argument 1: One Device Replaces a Dozen Points of Failure

The GE 845 (and its brother the Multilin 850) packs transformer protection, surge protection for AC units, and monitoring into a single unit that fits neatly inside our control panel box. Before, we had:

• A separate relay for overcurrent
• A separate differential relay
• Three different surge protectors for different voltage levels
• A standalone monitoring module
• About 40 extra wires connecting everything

That setup failed frequently. Not because any single component was bad, but because the interconnections were a nightmare – loose terminals, incompatible communication protocols, and zero visibility into what was happening. Seriously, I spent hours every month troubleshooting phantom trips. Switching to a GE 845 cut our wiring complexity by about 70% (and our monthly fault-finding time by, conservatively, 80%).

And here’s the part that surprised even me: the surge protection built into the 845 (which covers the AC unit feeding the transformer cooling fans) eliminated the exact issue that caused our first major outage. (Circa 2023, we had a voltage surge from a nearby pumping station – the relay caught it in milliseconds, zero damage.)

Argument 2: The “Plug a Surge Protector into Another Surge Protector” Trap

I know the question pops up: can you plug a surge protector into another surge protector? Technically, yes. Should you? Absolutely not – it’s a fire risk and a violation of NEC 285. But I see facilities try it all the time because they think daisy-chaining will protect more equipment with less cost. It doesn’t. Each additional protector adds impedance, reduces clamping voltage, and actually decreases protection.

With the GE 845, surge protection is designed for the entire transformer + load circuit in one calibrated stage. No daisy-chaining, no guesswork. The relay’s built-in monitoring even tells you when the MOVs are near end-of-life. That’s efficiency you can’t get from a $20 strip.

(As of January 2025, NEC 285.24 explicitly prohibits series connection of SPDs in the same panel – but the 845 integrates it at the correct point in the system, fully compliant.)

Argument 3: The Real Cost Isn’t the Hardware – It’s the Downtime

I went back and forth between a GE Multilin 850 and a competitor’s relay for about three weeks. The competitor was cheaper – maybe 20% less on the relay itself. But then I looked at the full lifecycle: the GE unit includes built-in surge protection (no extra purchase), plus integrated monitoring that sends alerts to our SCADA. Our old system required a separate surge protector for AC unit (another $400), a dedicated monitor (another $2,000), and regular calibration visits from an outside contractor (about $1,500/year).

With the 845, all that disappears. One device, one warranty, one communication cable to the plant network. That meant our accounting team saved about 6 hours of invoice processing per quarter – just from fewer vendors. Seriously, the paperwork savings alone paid for the premium within 18 months.

But Won’t You Lose Flexibility?

“But what if I need specialized protection that an all-in-one can’t provide?” – I hear this from operations engineers all the time. Fair question. The truth is, for 95% of applications up to 15kV (which covers our distribution transformers), the GE 845 offers enough programmability – 96 digital inputs, multiple communication protocols, custom logic with FlexLogic™ – to handle almost any scenario. If you’re running a niche high‑voltage test lab, sure, get discrete components. But for a typical industrial facility? The integrated approach is better.

(I’ll admit my experience is based on about 30 projects in manufacturing and utility settings. If you’re working with large-scale EHV transformers, you might need a different solution. But for the GE‑size range we deal with, the 845 is the sweet spot.)

Bottom Line: Efficiency Isn’t Just a Buzzword

So, if you ask me, the GE Multilin 845 (or the 850 if you need advanced arc-flash detection) is the only way to go for transformer protection. It eliminates messy daisy‑chaining of surge protectors, reduces panel clutter inside your control panel box, and most importantly, keeps your operations running when you can’t afford a single hour of downtime. The industry is moving toward integrated protection – don’t get left behind with a pile of separate boxes and a tangle of wires. Trust me, your purchasing process (and your accounting team) will thank you.