Installation manual

Why use "PV trigger"?

PV trigger prevents nuisance tripping of the crowbar protection in the following scenario.

A PLT/TRG 100C turbine (with an internal crowbar) is needed (for Outback FM60/80

controllers) because otherwise the turbine voltage might exceed 150V and damage the

controller. The crowbar short circuits the turbine for safety if the voltage exceeds 120V (see

5.3.3).

If any of the following conditions were to occur:

 Water element failure

 Breakers to FM60/80 accidently turned off

 Turbine breakers turned off (while turbine running)

 FM60/80 failure

 Cable break

the 120V internal crowbar inside the PLT100C would operate and the generation voltage

would drop to almost 0 VDC and the generation current would increase to the short circuit

rating. As the load on the turbine decreases the turbine will increase in speed.

If hydro generation stops it is almost certain that the crowbar has activated due to one of the

above conditions. If you go to the log data for the day you will almost certainly see a

recorded maximum voltage close to 120 VDC (note that due to cable voltage drop the MPPT

maximum recorded voltage will be less than 120 VDC to activate the Klampit, if your cable

has a high voltage drop you may still get nuisance tripping, this can be fixed by changing the

Klampit from 120 to 140 VDC). To get the turbine going again, stop the turbine at the valve,

locate and fix the cause, turn the turbine back on.

Using "PV trigger" (or similar settings in other MPPT regulators) has a number of

advantages when used with our PLT/TRG 40,100C and LH150 turbines namely:

 The turbine can be turned on quickly without fear of tripping the internal crowbar

(100C version).

 You will not get nuisance tripping while the MPPT unit sweeps.

 As the incoming voltage increases (as the battery reaches fully charged) more power

will be diverted to the water element.

MPPT regulators that can switch the input at high speed will generally work better. The KID

or the Midnite Classic MPPT range do a better job of input side switching and should be

used in preference to other products listed. This is covered in more detail in the 2014

Technical Manual.