Another told you to buy a plug-in protector. He did not say why.
Instead, he only promoted classic myth.

Meanwhile, this post will use numbers. A broken nuetral means a
voltage as much as but typically not close to 240 volts appears on your
120 volts. What will a plug-in protector do? It says right on the box
- let-throug voltage 330 volts. IOW it ignoreds voltages below 330
volts. It does nothing - remains just like an open switch - until the
rare 330+ volt transient occurs.

Numbers above demonstrate why plug-in protectors do nothing. Then we
add its joules rating that says the plug-in proetctor will save itself;
leaving the appliance to fend for itself.

One of the important reasons why your building has dedicated earthing
is so current can take another path. This particularly important
because without that earthing ground, then current may even take an
outgoing path via a gas line or other dangerous path.

How is your earth ground. Has your electric earthing been upgraded
to meet (and also exceed) post 1990 code requirements? If not, then
consider this to aleviate any future and more catastrophic failures.

And again, notice how many will not post like an engineer. Right
there on the box is the number that says a plug-in protector would have
nothing useful. Too many hear and believe myths rather than first
learn technical facts. The plug-in protector would have done nothing.
But your failure suggest you earthing mayt need inspection - and may
need enhancement. At minimum, you AC electric earthing (and all other
incoming utilities must connect to this) should meet post 1990 code
requirements.

Don't think in terms of some magic box. Think in terms of a
'system' solution. The 'system' require an earthing rod.

Brad wrote:
The branch of a tree broke and knocked out the
neutral wire to my sister's house. As a result, some of
her expensive electronics equipment was damaged.

I know about surge protectors, but I want to buy
a device/s (perhaps in a power strip) that creates a
"short" (and blows a fuse) when the AC voltage
goes above 180V.

Does anyone know where I can order it?