WIRING AND LOAD CENTER

Every system requires some wiring to connect the various components. Load centers are available as a complete package that easily facilitates the connection of loads and power source(s). All circuits in the system should use wire of adequate size and have fuses or breakers of sufficient capacity to carry the expected load current. Even the Stream Engine must be fused since it can suffer from a short or similar fault just like anything else in the system.

Inside the junction box on the side of the machine are two terminal blocks for the battery wiring. The negative terminal is bolted to the box and the positive terminal is bolted to the plastic plate. Your transmission wire ends are inserted into these two connectors (after being stripped of insulation) and then tightened.

The ammeter installed on the box will give a readout of the hydro output and is comparable to the speedometer of a car. A voltmeter connected to the batteries will roughly indicate the charge level, as described in Charge Level above, and is comparable to the gas gauge. 

DESIGN EXAMPLE

This example shows how to proceed with a complete installation.
The parameters of the example site are:

-120 feet of head over a distance of 1000 feet
-a flow of 30 gpm (most of the time)
-100 feet distance from the house to the hydro machine
-12 volt system

The first thing we do is determine the pipeline size. Although maximum power is produced from a given size pipe when the flow loss is 1/3 of the static head, more power can be obtained from the same flow with a larger pipe, which has lower losses. Therefore, pipe size must be optimized based on economics. As head decreases, efficiency of the system decreases, and it is important to keep the head losses low.

The pipe flow charts show us that two-inch diameter polyethylene pipe has a head loss of 1.77 feet of head per 100 feet of pipe at a flow rate of 30 gpm. This is 17.7 feet of loss for 1000 feet of pipe.

Using two-inch PVC gives us a loss of 1.17 feet of head per 100 feet of pipe or 11.7 feet for 1000 feet.

Polyethylene comes in continuous coils because it is flexible (and more freeze resistant). PVC comes in shorter lengths and has to be glued together or purchased with gaskets (for larger sizes). Let's say we select polyethylene.

The maximum output occurs with a flow of about 45 gpm since that gives us a head loss of 3.75 feet per 100 feet of pipe, or 37.5 feet of loss for our 1000 feet of pipe. This is 37.5' loss/120' head = 31% loss.

A flow of 30 gpm gives a net head of 102.3 feet (120' - 17.7'). The losses caused by the various pipe fittings and intake screen will further decrease the dynamic head, so 100 feet is a good working figure for the net head.

At this head and flow condition, the output of the machine is equal to about 300 watts.

Since we require 12 volts and the transmission distance is short, we can generate and transmit 12 volts using the Stream Engine. This Stream Engine could also be used for higher voltages like 24 and 48, and power could be transmitted longer distances.

Looking at the nozzle flow chart, we see that a 3/8" nozzle will produce a flow of 27.6 gpm at a 100' head. This is very close to the design point but will produce slightly less output than if we had exactly 30 gpm. A 7/16" nozzle would produce slightly greater flow and output. We need to go 100' with 300 watts at our site.  This will be about 20 amps at 15 volts at the generator. Note that there will be some voltage drop in the line and 12-volt batteries require somewhat higher voltages than nominal to become charged. So the 20 amps must pass through 200' of wire for the round trip. Resistance losses should be kept as low as economics permit, just like the pipeline losses. 

Let's say we wish to have around a 10% loss. This is 30 watts out of the original 300. The formula for resistive loss is I2R = watts when I = Intensity (current in amps) and R = Resistance in ohms.

(20 amps)2 x R (ohms) = 30 watts
400 amps x R (ohms) = 30 watts
R = 30 watts/400 amps
R = 0.075 ohms

This is the wire resistance that will produce a 10% loss. The wire loss chart shows loss per 1000', so:
1000'/200' x 0.075 ohms = 0.375 ohms per 1000'.

The chart shows 6 ga. Wire has a resistance of 0.40 ohms per 1000', so: 
200'/1000' x 0.40 ohms = 0.08 ohms.  This is close to the desired level. 20 amps x 20 amps x 0.08 ohms = 32 watts of loss. 

Increasing the wire size further reduces the losses. Voltage drop in the wire is equal to:  IR = 20 amps x 0.08 ohms = 1.6 volts

So if the battery voltage is 13.4 the generator will be operating at 15.0 volts. Keep in mind that it is always the batteries that determine the system voltage. That is, all voltages in the system rise and fall according to the battery's state of charge.

At the site, we would be generating 20 amps continuously. If we use lead acid batteries and wish to have two days of storage capacity, then:  20 amps x 24 hrs x 2 days = 960 amp. Hrs. Capacity

We would probably use an inverter and load controller with the system. The diagram for such a system would look like this:

Below: Diagram of a typical battery-based system: