PT-100 Manual

Operation

4.6 Arc-Fault Protection Operation

Arcs are caused by an intermittent connection and are dangerous because they are not an overload

or short-circuit, so the overcurrent protective device does not operate; however, they can burn

through wiring insulation or ignite nearby combustibles.

The PT controller has an integrated Arc-Fault Protection (AFP) circuit, which provides additional

protection against ﬁ res caused by an arc in the PV system. Arc-fault protection is required according

to the National Electrical Code (NEC) for PV systems operating at a maximum voltage of 80 volts

or greater. In accordance with Section 690.11 of the NEC, the AFP circuit should detect, indicate

and interrupt an arc-fault, and the fault indication should not be able to automatically reset/clear.

After a series arc-fault is detected, the PT controller shuts down and displays a F13 (AFP Fault)

code. Once the PT controller shuts down, the circuit is opened in an attempt to extinguish the

arc-fault in the PV system. When the PT controller has shut down from detecting an arc-fault, it

must be manually reset.

What is a series arc-fault? A “series” arc-fault results when the intended continuity of a current-

carrying conductor, connection, or component in series with the PV string and the load is failing.

This is different from a “parallel” (or short-circuit) arc-fault, which is a short between two current-

carrying conductors, or between a current-carrying conductor and a grounding conductor or other

grounded device. Series arc-faults occur when the PV array is producing current and a connection

in the PV electrical circuit becomes more resistive (i.e., unintentionally starts opening). This can

be caused by damaged conductors, or loose/corroded connections (either inside a PV module or

on a PV system component).

4.6.1 AFP Test Switch

The arc-fault test switch (see Figure 4-11) is provided to determine whether the arc-fault detection

circuit in the PT controller is functioning properly. When the arc-fault test button switch is pressed

and released, a simulated arcing condition is generated and the AFP circuit must be able to detect

this arcing condition and cause the PT controller to shut down.

To perform an arc-fault protection circuit test:

1. First ensure the PT controller is on and operating, PV power is available and connected to the

PT controller’s PV input, and DIP switch 1 is DOWN (ARC fault detection is enabled).

2. Quickly press and release the arc-fault test button switch (under the access cover).

Info: The arc-fault test switch is a small momentary type button switch which operates

by lightly pressing and releasing the top of the switch. Be careful not to apply too much

force to the top or side of the switch when pushing—or the switch might break.

3. The fault LED (red) and ARC fault LED (red) comes on, F13 (AFP Fault) code displays, and the

PT controller shuts down.

4. The PT controller must not resume operation until the AFP fault is manually cleared (either by

pressing the RESET pushbutton for one second, or removing all power from the PT controller).

If all four steps passed, then the arc-fault circuit inside the PT controller is functioning properly.

If the AFP circuit test fails:

1. Ensure there is sufﬁ cient PV power connected to the PT controller’s input—this test cannot be

performed unless there is sufﬁ cient PV power to produce an arc.

2. Ensure the arc-fault detection circuitry is enabled by verifying DIP switch #1 is DOWN.

Figure 4-11, AFP Test Switch

AFP Test Switch

ARC Fault LED

DIP Switch #1 is DOWN