What Causes Fuses to Blow and Tips to Ensure Safe Heater Operation
Fuses blow when the draw (amps) is higher than the fuse is designed to permit. With the BREWHA brewing systems, this is typically caused by: 1. a short where the draw can suddenly spike, 2. power demand being too high, or 3. heat buildup in the control box.
1. As for the first cause (a short), check all your wires and connection points to ensure they are snug. If a connection point is heating up when the power is on (e.g. extension cord connectors can be warm to touch during 100% output, but should not be hot) it indicates a poor connection inside and the power should be disconnected and the wire terminals inspected and tightened.
Always ensure that heater connectors are twisted tightly upon connection to ensure a tight connection. Our heater connectors are the locking style of connector so need to be twisted to be fully connected.)
Connections can loosen over time due to heating/cooling, and especially if water has entered the connection (care should be taken during cleaning and storage to ensure water does not enter the connector). When that water expands rapidly upon heating, it can push connections apart causing a gap across which electricity starts to jump (arc); this causes extra heating and can damage the connector as well as leading to blown fuses.
It is important to never connect power cords when the power is turned on. (This is true for all applications, but especially high draw (high voltage and amps) like these heaters. First connect the heaters snugly, THEN turn the power on. Connecting when they are live, sees arcing as the contacts draw close; this arcing will damage the connectors over time and lead to failure.
2. Demand is too high if the power requirement exceeds the rating of the fuse. For BREWHA customers, it is important to ensure that the power supply is understood correctly, and that the correct heaters chosen for the supply. BREWHA offers 208V and 240V heaters and each are designed to provide 5500W of heating at that voltage. Since resistance heaters are designed for output based on the anticipated volts, if a 208V heater is purchased, but is supplied with 240V, the power output will exceed 5500W and the amps will also be higher. Voltage coming to your brewery varies by location and even time of day since local demand on the electrical grid causes it to change. So if the supply is higher than the rating, fuses might only occasionally blow.
To check your voltage, confirm it by using a multimeter on AC volt selection (hire an electrician for this if not confident). Placing the multimeter probes across the two hots (for single phase) on the distribution block will confirm your voltage; typically this will be at or below 240V for single phase (it can fluctuate throughout the day between 210-240V). In North America each leg of single phase power is 120V, so placing your multimeter across a hot and a neutral will show 120V, across both hots will show ~240V. For three phase power, place the multimeter across all three poles (A-B, B-C and C-A). Newer 3 phase installs in North America will show ~190-208V across all three poles, but older installs might have a ~210-240V 'high leg' across two of the poles. If this is your situation, you will need to use 240V rated heaters, rather than the 208V ones that are typical for three phase.
3. Solid state relays (SSR) inside the control box enable the brewer to interrupt the amount of power going to the heaters, to permit less than 100% output. Being able to control heater output is useful during mash and fermentation, when reduced power to the heaters can reduce the risk of scorching, and during the boil, to enable control over how much water is being boiled off. Without the SSRs, the power would either be only fully on, or fully off. Power flowing through the SSRs however, does generate heat, and as the temperature of the SSRs increase, they become less effective, drawing more current. So to keep them operating well, it is important to ensure that the box is ventilated and the cooling fan (on larger controllers) is working optimally.
During heatup on the fan cooled controllers (this is especially true when the cooling fan was installed in an orientation to draw air out of the box) it is recommended to keep the lid closed so that the fan moves fresh air throughout the box, rather than just past the front plate and out the side. For the single heater controllers without a fan, it is recommended to keep the lid open, and always installed on a wall (never lying flat on a table). Also, the air filters (on some controllers) can severely restrict air flow (especially if dirty) so should not be used unless the controller is in a very dusty environment. For optimal performance, the air temperature inside the control box should remain below 45C/113F.
Volts and amps are relatively easy and inexpensive to confirm and there are lots of videos online about how qualified personnel would go about that. To check heater functionality the resistance can be measured with an ohm/multimeter. The two formulas you need (there is math in brewing!) are: Ohms=Volts/Amps and Amps=Watts/Volts (for the 9500W three phase heaters the Watts for each rod are 1/3 of total).
2 comments
We can sell you fuses. Email us at brewing@brewha.com.
Do you guys sell the fuses?