Question
Is there a maximum limit to mains frequency range that appliances will accept (e.g. if they conform to UK or EU standards?)
e.g. The Dynamic Demand web site indicates that there is a legal limit of about 49.5 Hz to 50.75 Hz (lines on the meter).
Why?
I'm configuring an Amber Switch (CAS-I-B) to turn on/off a hot water if the mains frequency is increased/decreased respectively, which in turn is performed by the inverter if the batteries are fully charged.
Note: the inverter is powered by a DC solar/battery system (no grid tie).
I'd like to increase the frequency to 53.5 Hz or even higher, but before doing that, wanted to know what the official limits are. Obviously individual appliances may be higher, as they could be manufactured to operate in countries with lower quality power. What kind of appliances should look out for in particular that are likely to be a constraint?
My guess is that AC motors are the most likely culprit as the higher frequency may make them run faster, so around the house that would be water pumps, refigerators and plug-in vacuum cleaners.
What is the most likely 'damage to equipment' one would see with wildly varying mains frequencies?
Best Answer
Amber Switches are not needed to protect the loads but are exclusively designed for "islander" renewable low power generators with no energy storage.
The spec here is load regulated generator frequency which lowers in RPM or Hz under high loads and rises above norm, with low loads.
If you are not the owner of the grid and live in the U.k. where the freq. tolerance is adequate, there is no purpose to be served here.
Unless you are participating in "load shedding" for reduced rates, there is no need to do this.
The Amber Switch has a hysteresis of 0.25 Hz which can be set to a very limited range value for 50 or 60Hz
Keep in mind heavy motor loads are 5 to 8x rated full power when switched ON unless custom low surge designed. This is far greater than a 5% frequency change that occurs very slowly or even a 1~2 swing as noted in the UK. Here in Toronto, we can sync our OCXO's to the grid.(lol)