Xantrex PV 20208 User Guide

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OPERATION and MAINTENANCE

MANUAL

for

MODEL PV-20208

20 KW Grid-Tied

Photovoltaic Inverter

Document #151119

Revision B November 10, 2000

IMPORTANT SAFETY INSTRUCTIONS

SAVE THESE INSTRUCTIONS - THIS MANUAL CONTAINS IMPORTANT INSTRUC-

TIONS FOR TRACE TECHNOLOGIES MODEL PV-20208 GRID TIED PHOTOVOLTAIC

INVERTER THAT SHALL BE FOLLOWED DURING INSTALLATION AND MAINTENANCE

OF THE PV-20208.

Xantrex Technologies Inc./Trace Technologies Corp.

161-G SOUTH VASCO ROAD

Livermore, CA 94550

(925) 245-5400

T able of Contents

Section 1: Product Description

Introduction

Major Components

Interconnection Standards Compliance

Specifications

Equipment Symbol

Section 2: Safety

Safety Features

Isolation Procedure

Anti Island Protection

Section 3: Installation And Initial Turn-On

Isolation Transformer Requirements

T orque and Wire Gauge Specifications

Installation Instructions

Interconnection Wiring

Initial Turn On Procedure

Section 4: Operation

Description of System Operation

Operator Interface Panel (LED and LCD)

Example of Normal System Operation

Section 5: Troubleshooting

General

Fault Conditions and Troubleshooting

Fault Clearing

Fault Descriptons and Troubleshooting

Section 6: Preventative Maintenance

Isolation Procedure

Turn-On Procedure

Section 7: Drawings and Major Parts Lists

System Schematic, Grid Tied PV Inverter , PV-Series

Assembly Drawings And Major Parts Lists

Envelope Drawing, Grid Tied PV Inverter , PV-20208

UL Listing Document, April 25, 2000

UL Listing Card, September 8, 2000

Accessories

SECTION 1

PRODUCT DESCRIPTION

PV-20208 Photovoltaic Inverter

Operation and Maintenance Manual

DOCUMENT: 151119

1-1

INTRODUCTION

The Trace Technologies Model PV-20208 is a 20KW Grid Tied Photovoltaic Inverter. It utilizes ad-

vanced power electronics to allow interface of a photovoltaic array with a utility grid. The PV-20208 is

a highly integrated assembly, consisting of an inverter bridge and associated control electronics all on

a single board. The PV-20208 control software provides for complete overall system control with a

variety of protective and safety features.

MAJOR COMPONENTS

The major components of the PV-20208 are identified in Drawing No. 151121.

Main Enclosure

The enclosure (shown in Figure 1-1) is NEMA-4 rated. The PV-20208 enclosure contains the Inte-

grated Bus Board, output line filter (insuring that the PV-20208 line currents and voltages meet IEEE-

519 harmonic distortion requirements), control power transformers, and A/C contactor (PV-20208 A/

C output to the grid). Also found within the enclosure are the system protection devices (control power

circuit fuses). The front door of the enclosure contains the operator interface panel (three LED’s or

LCD and an on/off switch).

Figure 1-1

Figure 1-2

SECTION 1

PRODUCT DESCRIPTION

PV-20208 Photovoltaic Inverter

Operation and Maintenance Manual

DOCUMENT: 151119

1-2

Integrated Bus Board

The PV-20208 design makes use of a fully integrated bus board as shown in Figure 1-2. The bus board

assembly is mounted to an aluminum extrusion heat sink, which mounts through an opening in the

back of the enclosure. The power electronics is comprised of a six pack of IGBT devices, mounted to

the heat sink. The bus board is mounted on top of the IGBT six pack device, and is supported through

a series of standoffs attached to the heat sink.

The bus board contains all of the necessary control functions to drive the (attached) switching transis-

tors. The bus board contains the following functional circuits: D/C control power supplies (+5V, +/-

15V and four isolated +15V sources for the IGBT’s), A/C and D/C high voltage measurement, A/C and

ground current measurements, contactor and indicator controls, discrete input sensing (on/off switch),

and closed loop PWM modulators. The bus board contains a micro-controller chip to perform the low-

level control functions associated with the collection of measurement and driving the pulse width

modulators.

A plug in DSP module controls the bus board. The DSP module is designed to the industry standard,

PC-104 specification, and is used to perform the majority of the calculations needed to control the bus

board. The most significant tasks are: control of PV-20208 electromechanical components and power

electronics converters, signal conditioning (digital filtering and transformations), and communication

with the operator interface panel and system sensors.

The PV array ties directly to the DC bus. The inverter controller manages the transfer of power between

the DC bus and the utility grid.

INTERCONNECTION STANDARDS COMPLIANCE

The PV-20208 has been tested and certified by Underwriters Laboratories to be in compliance with

UL1741 Static Inverters And Charge Controllers For Use In Photovoltaic Power Systems, as well

as IEEE-P929 Recommended Practice For Utility Interface Of Photovoltaic (PV) Systems.

IEEE-P929 provides guidance regarding equipment and functions necessary to ensure compatible op-

eration of photovoltaic systems which are connected in parallel with the electric utility. UL1741 is the

test procedure performed by Underwriters Laboratory on the PV-20208 to verify it meets the recom-

mendations of IEEE-P929. Refer to both documents for details of these recommendations and test

procedures.

CAUTION

The fuses within the PV-20208 are intended for protecting the PV-20208 control cir-

cuitry only. They are not intended to provide protection for the PV array or external

cabling.

SECTION 1

PRODUCT DESCRIPTION

PV-20208 Photovoltaic Inverter

Operation and Maintenance Manual

DOCUMENT: 151119

1-3

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EQUIPMENT SYMBOL

Chassis ground – Customer supplied system ground connection point. This symbol may be found near

a stud within the main enclosure. It is provided as a location to bond the electrical system equipment

ground.

*If ambient temperature is between -20 to 0° C, the unit must be powered up in standby for at least

one hour prior to going on-line.

SPECIFICATIONS

The PV-20208 has been designed for photovoltaic power systems, which operate within the following

specifications. Application of the PV-20208 in a manner inconsistent with these specifications may

cause damage to the PV-20208 and other system components, and is a violation of the terms of the

warranty.

DOCUMENT: 151119

SECTION 2

SAFETY

PV-20208 Photovoltaic Inverter

Operation and Maintenance Manual

2-1

SAFETY FEATURES

Front Panel Indicators

The PV-20208 incorporates three colored LED indicators, used to show the current operating state of

the inverter. The indicators have the following meanings:

• Red: Fault Mode - The inverter has sensed an abnormal condition. To reset the unit (clearing the

fault condition), cycle the on/off switch (see below).

• Amber: Sleep Mode – The inverter is waiting for sufficient PV voltage to start the inverter.

• Green: Operator Mode - The inverter is active and generating A/C current.

On/Off Switch

The PV-20208 incorporates a maintained position on/off switch located on the front door of the enclo-

sure. Under normal conditions, the on/off switch in the on position. Turning the switch to the off

position will initiate a controlled shutdown of the PV-20208 and open the main contactor within the

unit. The PV-20208 is prevented from being restarted until the on/off switch is turned back to the on

position. Cycling the on/off switch will reset the PV-20208 and attempt to clear any system fault.

Main Enclosure Door

The front door of the PV-20208 main enclosure is pad lockable. It is recommended that the PV-20208

enclosure door be padlocked during normal operation.

Fault Reporting

Any fault conditions are reported to the operator interface. If the PV-20208 is equipped with LED’s,

the red LED will light and the green LED will flash the corresponding number of the fault. If the PV-

20208 is equipped with the LCD option, the LCD will display a text description of the fault. Refer to

Section 5, Troubleshooting, for detailed descriptions of system fault conditions.

PV Ground Fault Detection

The PV-20208 is equipped with ground fault detection circuitry and control. The single point of PV

The PV-20208 enclosure contains exposed high voltage conductors. The enclosure

door should remain closed, except during maintenance or testing. These servicing

instructions are for use by qualified personnel only. To reduce the risk of electric

shock, do not perform any servicing other than that specified in the operating

instructions unless you are qualified to do so. Do not open the cabinet door if

extreme moisture is present (rain or heavy dew).

WARNING

The PV-20208 does not incorporate a door interlock switch. Please make sure the

unit is powered down, and isolated from the utility grid and PV panels, prior to

opening the enclosure door. (Allow 5 minutes for any stored potentials to be dis-

charged, prior to opening the unit). The front door of the PV-20208 main enclosure

is pad lockable. It is recommended that the PV-20208 enclosure door be padlocked

during normal operation.

WARNING

DOCUMENT: 151119

SECTION 2

SAFETY

PV-20208 Photovoltaic Inverter

Operation and Maintenance Manual

2-2

The terminals of the PV input may be energized if the arrays are energized. In

addition, allow 5 minutes for all capacitors within the enclosure to discharge after

disconnecting the PV-20208 from AC and DC sources.

WARNING

ISOLATION PROCEDURE

The following procedure should be followed to de-energize the PV-20208 for maintenance:

ANTI ISLAND PROTECTION

A digital phase-shift-loop (PSL) circuit is implemented in the DSP inverter controller to prevent

“Islanding” of the PV-20208.

The DSP continuously makes minor adjustments to the power factor phase angle above and below

unity. In the event of a utility outage, these adjustments destabilize the feedback between the inverter

and the remaining load, resulting in an over/under frequency or voltage condition. The PV-20208

then performs an orderly shutdown. The fault condition will remain until the utility voltage and

frequency have returned to normal for 5 minutes.

This method has been extensively tested and proven to exceed the requirements of UL 1741.

system ground must be routed through CT1 on the main control board (see section 3, installa-

tion and section 7, system schematic for further detail). Upon detection of 1.5 amps of ground

fault current, the PV-20208 executes an orderly shutdown, and annunciates a ground fault at the

operator interface. The PV-20208 will remain faulted until the ground fault is remedied and

cleared at the operator interface (see section 5, troubleshooting).

1. Turn the on/off switch to the off position.

2. Open the PV array disconnect switch (if present).

3. Open the AC interface disconnect (if present).

4. Open the isolation transformer circuit breaker.

5. Install lockout devices on the isolation transformer circuit breaker and PV disconnect switch (if

present).

SECTION 3

INSTALLATION AND INITIAL TURN-ON

PV-20208 Photovoltaic Inverter

Operation and Maintenance Manual

DOCUMENT: 151119

3-1

ISOLATION TRANSFORMER REQUIREMENTS

The PV-20208 is required to have an isolation transformer wired between the inverter AC output and

the utility interconnection. Any standard dry-type isolation transformer is compatible with the PV-

20208 as long as the inverter side is rated for a minimum of 20KVA continuous duty.

Inverter Side Isolation Transformer Requirements

The inverter side transformer windings may be configured either delta or WYE, and must be rated for

208 VAC. Trace Technologies recommends using a delta wound transformer to avoid installation mis-

takes. If a WYE wound transformer is used to interface with the PV-20208, and the PV array is

grounded, the neutral (X0) must be left floating. If the neutral is tied to ground, the inverter will not

function properly , and may be damaged.

Utility Side Isolation Transformer Requirements

The utility side isolation transformer windings may be configured either delta or WYE, and must be

rated for the utility voltage at the point of utility inter-connection. Check with the utility of jurisdiction

when selecting an isolation transformer configuration. If a WYE wound transformer is used to interface

with the utility , it is not necessary to connect the neutral (X0) to ground. The PV-20208 is a balanced,

three phase, current sourcing inverter, and only operates with the presence of a stable utility voltage.

Single phase grounded loads which may be present between the transformer and utility, will maintain

their existing ground reference at the utility distribution transformer . Grounding the neutral of a WYE

wound transformer may create an “open delta” condition, depending on the utility configuration. This

condition may keep the PV-20208 from detecting a loss of phase condition on the utility system,

which may allow potentially lethal voltage to be present on the open phase wiring.

Contact your Xantrex/Trace Technologies distributor if you have any questions regarding isolation

transformer requirements.

Check with the local utility of jurisdiction when selecting the winding configura-

tion of the isolation transformer. Individual utilities may have unique require-

ments related to isolation transformer wiring. Some winding configurations may

keep the PV-20208 from detecting a loss of phase condition on the utility system

which may allow potentially lethal voltage to be present on the open phase wir-

ings.

WARNING

TORQUE AND WIRE GAUGE SPECIFICATIONS

The following torque specifications are to be used on all electrical interfaces made during installation

of the PV-20208.

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T orque Table

SECTION 3

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PV-20208 Photovoltaic Inverter

Operation and Maintenance Manual

DOCUMENT: 151119

3-2

All wiring methods shall be in accordance with the National Electrical Code ANSI/

NFPA 70. All power conductors interfacing to the PV-20208 should be sized in

accordance with the National Electric Code ANSI/NFP A 70 and local codes. Large

gauge wire must have a minimum bend radius dependent upon the wire gauge

(refer to the National Electric Code, Article 373-6B). Take care to keep the wire

bundles away from any sharp edges which may damage wire insulation over time.

Trace Technologies recommends using No. 6 AWG, 105 degrees C, minimum,

copper wire for all connections with the PV-20208.

CAUTION

Ventilation Considerations

1. Maintain a minimum 6” clearance above and below the PV-20208 for proper cooling fan operation.

2. Maintain a minimum 1” clearance to the left and right of the PV-20208.

Installation

1. The unit must be mounted at least 3’ off the ground, and 12” above any horizontal surface.

2. Screw two 3/8” x 3-1/2” long lag bolts into existing studs in the wall (16-inch mounting center) at

lower mounting level on PV-20208. Lag bolts should be horizontally level with each other. Leave

a minimum of 1” of bolt protruding from the wall.

3. Place the PV-20208 bottom mounting ears, shown in Figure 3-1 and Figure 3-2 onto installed lag

bolts. (See following page.)

4. Hold the unit against wall and install upper lag bolts (3/8” x 3-1/2”). Tighten bolts firmly.

5. Tighten lower lag bolts while unit is held in place.

6. Install two 1-1/2” liquid tight connectors (included with the PV-20208) where shown in

Figure 3-3. (See following page.)

INSTALLATION INSTRUCTIONS

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The following table shows acceptable wire gauges to be connected to the PV-20208 AC and DC

inputs.

Wire Gauge Table

Figure 3-1

SECTION 3

INSTALLATION AND INITIAL TURN-ON

PV-20208 Photovoltaic Inverter

Operation and Maintenance Manual

DOCUMENT: 151119

3-3

Figure 3-2

Figure 3-3

LIQUID TIGHT CONNECTORS

Array Grounding and Ground Fault Detection

If grounding the PV array is required for monopolar or

bipolar arrays, jumper TB1-2 to a (PV-) cabinet ground

stud. If ground fault detection is required, route this

jumper through CT1 located on the lower right hand

corner of the control board (see the system schematic

for further detail). This must be the only point of PV

grounding for the PV-20208 and the ground fault

detection system to function properly .

CONTROL BOARD & CT1

CT1

The input and output circuits are isolated from

the enclosure, and that system grounding, if re-

quired by sections 690-41 and 690-42 of the Na-

tional Electric Code, ANSI/NFPA 70, is the

responsibiliy of the installer.

CAUTION

SECTION 3

INSTALLATION AND INITIAL TURN-ON

PV-20208 Photovoltaic Inverter

Operation and Maintenance Manual

DOCUMENT: 151119

3-4

To reduce the risk of fire, connect only to a cir-

cuit provided with 90 amperes maximum branch

circuit overcurrent protection in accordance with

the National Electrical Code, ANSI/NFPA 70.

CAUTION

INTERCONNECTION WIRING

The following wires for connecting the PV-20208 to ex-

ternal devices are not provided by Xantrex/Trace Tech-

nologies: (See wiring diagram on the following page.)

Phase-Sequencing

The PV-20208 is equipped with an automatic phase-

detection control algorithm. This allows the utility

interface conductors to be connected in any sequence

convenient at the time of installation. Upon system

initialization at power-up, the PV-20208 determines

the phase sequence of the utility connection and

configures the modulator drivers accordingly .

• 3-Phase 208 VAC inverter output (main contactor, see picture) to terminals of the 208 VAC delta

side of isolation transformer. If the inverter side of the isolation transformer is configured

WYE and the PV array is grounded, the neutral must be left floating. Ground loops will

exist when the inverter starts switching, which will cause the inverter to shut down due to

phase over-currents and may result in damage to the PV-20208. Also, insure that this

neutral is not bonded to the isolation transformer frame.

• System ground to the isolation transformer chassis ground.

• Isolation transformer grid side terminals to line circuit breaker (or the AC disconnect switch if

present).

• PV frame ground to PV-20208 enclosure chassis ground stud.

• PV-20208 enclosure chassis ground stud to the electrical distribution system ground.

• PV+ to the inverter enclosure terminal block TB1-1.

• PV- to the inverter enclosure terminal block TB1-2.

Install all wires listed above. Refer to the system schematics in Section 7 for more detailed terminal

locations.

MAIN CONTACTOR

SECTION 3

INSTALLATION AND INITIAL TURN-ON

PV-20208 Photovoltaic Inverter

Operation and Maintenance Manual

DOCUMENT: 151119

3-5

Wiring Diagram

Frame

Ground

Line Circuit

Breaker

Isolation

Transformer

PV-20208

Inverter

To Single Point Electrical

Distribution System Ground

PV Array

Trace Combiner Box

(Optional)

X1 H1 X2 H2 X3 H3

PV+

PV-

+ 26 hidden pages