The Siren Board

Hey everyone,

As some of you know, the city of Independence, OH (in Cuyahoga County) has a variety of sirens including several 5AT's (technically 7AT's) and two Federal Enterprises Thunderbolt 1000's that were from the original CD system which went up in April 1952 around Cleveland and Cuyahoga Co.

Anyways the 5T's are wired up quite strangely. They are 480V 3 Phase.
They are almost like using transformers or something. Anyone know what these are? I've never seen such a weird wiring setup before. All of them are wired like this. I'd post more photos, but apparently for whatever reason, ARS won't let me post pics over 1 MB.

They are for the electric meter. They don't pass 480 through a meter like they do on lower voltages. These are basically a clamp current meter.

kb8vul wrote: ↑

Mon May 13, 2019 10:44 am

They are for the electric meter. They don't pass 480 through a meter like they do on lower voltages. These are basically a clamp current meter.

So if that is for the electric meter, then how does the 480V 3 Phase power get to the actual siren?

The power is hooked up to the siren, and the black clamps you see go around the wire measure the current by measuring the magnetic field produced around the cable when the siren draws power.

The true name for them is 'current transformer';

https://en.wikipedia.org/wiki/Current_transformer

basically, they provide a fixed ratio of current output to the measuring meter for a certain current thru the main conductor passing thru them; like 10:1
For every 10 amps of electrical current thru the main conductor (the big electrons) the meter will read it as 1 amp from the other leads of the transformer. This way, you can get away with a smaller (less expensive) electric power meter.

Thanks for the help!
I’d attempt to film one again but these sirens seem to fail as the FC’s on them are either bad or they don’t receive the single tone strong that’s sent out and obviously since dispatch can’t tell what sirens activate or not and only send out one string, these sirens usually fail monthly tests. Nevertheless I’ll try and film one probably this summer.