Installation manual

6.8. Key to wiring diagrams.

These wiring diagrams are an easy to follow representations of typical systems. All

installations must give regard to:

 Local and national regulations

 Advice in this document

 Advice in manuals for supporting products shown

Where such advice conflicts or is unclear, you should seek advice from an experienced

renewable energy installer who is familiar with these products and regulations that apply in

your country.

DB - Double Pole DC breakers (HRC fuses can also be used).

SB - Single Pole DC breakers (HRC fuses can also be used).

SB1-SB5 provide the same functions as BD1-BD5 below, but are single

pole breakers.

DB1 - DC breakers (in waterproof enclosure if turbine is outside) rating

should be at least 25% more than turbine's rated amps (see nameplate),

and be low enough to protect the cable if necessary. Bear in mind that

the turbine may produce more than expected, so the size of this breaker may need to be re-

evaluated once installed.

Short circuits will not damage the turbine alternator. Provided the cable is large enough to

handle the turbine's short circuit current then there is no upper limit to breaker size. In such

cases an isolator switch could be substituted if desired.

DB1 is a termination point for the turbine power lead, enables Voc measurements to be

taken at this location and provides overcurrent protection to the cable if necessary. DB1 may

be omitted if the cable length is short. Then only install DB2.

DB2 - DC breaker is of the same rating as DB1. It is located at the end of the

supply cable from the hydro turbine and prior to the battery bank, MPPT controller

or grid-connect inverter. It may be omitted if a suitable breaker is already provided

in the connected equipment. DB2 is a termination point for the turbine supply

cable, enables Voc measurements to be taken at this location and provides

overcurrent protection to the cable if necessary.

DB3 - DC breaker on the output of the MPPT controller. Minimum size is 25%

more than the maximum output generation amps into the battery. Maximum rating

should be similar to the maximum output rating of the MPPT controller, or its

battery cable (which ever is the lower).

For example 63 amp breakers are commonly used on 60 amp MPPT controllers

(provided the wiring is suitable for this current). The breaker may be omitted if MPPT

manufactures’ instructions do not require it. DB3 is a termination point, enables

easy on/off selection and provides overcurrent protection. Picture shows DB2

and DB3 in common housing external of the MPPT controller.

DB2 and DB3 may already be integrated into the MPPT controller as shown on

the right.

DB4 - DC breaker on the diversion load circuit. Rating should be 1.5-2.0 x the

maximum rating of the element. It may be omitted if the MPPT/PWM controller

instructions do not require it but we advise installing this breaker. DB4 is a

termination point and provides overcurrent protection to the cable. It may be