Danfoss VLT® 6000 HVAC User guide

Brand: Danfoss

Model: VLT® 6000 HVAC

Type: User guide

VLT

6000 HVAC Series

■ Contents

Introduction to HVAC

...................................................................................... 4

Software version ....................................................................................................... 4

Safety regulations ..................................................................................................... 5

Warning against unintended start ............................................................................. 5

Introduction to the Design Guide .............................................................................. 6

Available literature ..................................................................................................... 8

Why use a frequency converter for controlling fans and pumps? .............................. 8

The clear advantage - energy savings ...................................................................... 8

Example with varying flow over 1 year .................................................................... 10

Better regulation ..................................................................................................... 11

Frequency converters generate less noise .............................................................. 11

Simpler installation when using a frequency converter ............................................ 11

V-belts no longer required ...................................................................................... 11

Regulating dampers and valves no longer required ................................................. 11

Cos ϕ compensation .............................................................................................. 11

Star/delta starter or soft-starter not required ........................................................... 11

Cost of using frequency converter not higher ......................................................... 11

Control principle ..................................................................................................... 13

CE labelling ............................................................................................................ 14

Application examples ............................................................................................. 14

Variable Air Volume ................................................................................................. 15

The new standard .................................................................................................. 15

Constant Air Volume ............................................................................................... 16

The new standard .................................................................................................. 16

Cooling Tower Fan ................................................................................................. 17

The new standard .................................................................................................. 17

Condenser pumps ................................................................................................. 18

The new standard .................................................................................................. 18

Primary pumps ....................................................................................................... 19

The new standard .................................................................................................. 19

Secondary pumps .................................................................................................. 20

The new standard .................................................................................................. 20

Choice of frequency converter ................................................................................ 21

Unpacking and ordering a VLT frequency converter ................................................ 25

Type code ordering number string ......................................................................... 25

Ordering form ......................................................................................................... 28

PC software and serial communication ................................................................... 29

PC Software tools .................................................................................................. 29

Fieldbus options ..................................................................................................... 29

Profibus .................................................................................................................. 29

LON - Local Operating Network ............................................................................. 30

DeviceNet .............................................................................................................. 30

Modbus RTU .......................................................................................................... 30

Installation ......................................................................................................... 39

General technical data ............................................................................................ 39

Technical data, mains supply 3 x 200-240V ............................................................ 43

Technical data, mains supply 3 x 380-460V ............................................................ 45

Technical data, mains supply 3 x 525-600 V ........................................................... 50

Fuses ..................................................................................................................... 53

Mechanical dimensions .......................................................................................... 55

MG.60.B9.02 - VLT is a registered Danfoss trademark

VLT

6000 HVAC Series

Mechanical installation ............................................................................................ 59

IP 00 VLT 6400-6550 380-460 V ............................................................................ 61

General information about electrical installation ...................................................... 62

High voltage warning .............................................................................................. 62

Earthing .................................................................................................................. 62

Cables .................................................................................................................... 62

Screened/armoured cables .................................................................................... 62

Extra protection with regard to indirect contact ....................................................... 62

RFI switch .............................................................................................................. 63

High voltage test .................................................................................................... 64

Heat emission from VLT 6000 HVAC ...................................................................... 65

Ventilation of integrated VLT 6000 HVAC ................................................................ 65

EMC correct electrical installation ........................................................................... 65

Use of EMC-correct cables .................................................................................... 68

Electrical installation - earthing of control cables ..................................................... 69

Electrical installation, enclosures ............................................................................. 70

Tightening-up torque and screw sizes .................................................................... 78

Mains connection ................................................................................................... 78

Motor connection ................................................................................................... 78

Direction of motor rotation ...................................................................................... 79

Motor cables .......................................................................................................... 79

Motor thermal protection ........................................................................................ 80

Earth connection .................................................................................................... 80

Installation of 24 Volt external DC supply ................................................................ 80

DC bus connection ................................................................................................ 80

High-voltage relay ................................................................................................... 80

Control card ........................................................................................................... 80

Electrical installation, control cables ........................................................................ 81

Switches 1-4 .......................................................................................................... 82

Bus connection ...................................................................................................... 82

Connection examples, VLT 6000 HVAC .................................................................. 83

Programming .................................................................................................... 85

Control unit LCP ..................................................................................................... 85

Control keys for parameter setup ........................................................................... 85

Indicator lamps ....................................................................................................... 86

Local control .......................................................................................................... 86

Display mode ......................................................................................................... 87

Navigation between display modes ........................................................................ 89

Changing data ........................................................................................................ 90

Manual initialisation ................................................................................................. 90

Quick Menu ............................................................................................................ 91

Operation and Display 001-017 .............................................................................. 93

The Setup configuration ......................................................................................... 93

Setup of user-defined readout ................................................................................ 94

Load and Motor 100-117 ..................................................................................... 100

Configuration ........................................................................................................ 100

Motor power factor (Cos ø) .................................................................................. 106

Reference handling ............................................................................................... 108

Reference type ..................................................................................................... 111

Inputs and outputs 300-328 ................................................................................. 116

Analogue inputs ................................................................................................... 119

Analog/digital outputs ........................................................................................... 122

Relay outputs ...................................................................................................... 125

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VLT

6000 HVAC Series

Application functions 400-427 .............................................................................. 128

Sleep mode .......................................................................................................... 129

PID for process control ......................................................................................... 133

PID overview ........................................................................................................ 136

Feedback handling ............................................................................................... 136

Serial communication for FC protocol ................................................................... 141

Protocols .............................................................................................................. 141

Telegram communication ..................................................................................... 141

Telegram build-up under FC protocol ................................................................... 142

Data character (byte) ............................................................................................ 143

Process word ....................................................................................................... 147

Control word according to FC protocol ................................................................. 147

Status word as per FC protocol ............................................................................ 148

Serial communication reference ............................................................................ 149

Present output frequency ..................................................................................... 150

Serial communication 500 - 556 ........................................................................... 151

Extended status word, warning word, and alarm word ......................................... 158

Service functions 600-631 .................................................................................... 161

Electrical installation of the relay card .................................................................... 166

All about VLT 6000 HVAC .......................................................................... 167

Status messages .................................................................................................. 167

List of warnings and alarms .................................................................................. 169

Aggressive environments ...................................................................................... 174

Calculation of resulting reference .......................................................................... 174

Galvanic isolation (PELV) ....................................................................................... 175

Earth leakage current ........................................................................................... 175

Extreme running conditions .................................................................................. 176

Peak voltage on motor ......................................................................................... 177

Switching on the input .......................................................................................... 177

Acoustic noise ...................................................................................................... 178

Derating for ambient temperature ......................................................................... 178

Derating for air pressure ....................................................................................... 179

Derating for running at low speed ......................................................................... 179

Derating for long motor cables or cables with larger cross-section ....................... 179

Derating for high switching frequency ................................................................... 179

Vibration and shock .............................................................................................. 180

Air humidity ......................................................................................................... 180

Efficiency ............................................................................................................. 181

Mains supply interference/harmonics .................................................................... 182

Power factor ........................................................................................................ 182

EMC test results (Emission, Immunity) .................................................................. 184

EMC Immunity ..................................................................................................... 185

Definitions ........................................................................................................... 187

Parameter overview and factory settings .............................................................. 189

Index .................................................................................................................... 196

MG.60.B9.02 - VLT is a registered Danfoss trademark

VLT

6000 HVAC Series

■Software version

175ZA692.12

VLT 6000 HVAC

Design Guide

Software version: 2.6x

This Design Guide can be used for all VLT 6000 HVAC

frequency converters with software version 2.6x.

The software version number can be seen from parameter

624.

MG.60.B9.02-VLTisaregisteredDanfosstrademark

VLT

6000 HVAC Series

Introduction to

HVAC

The voltage of the frequency converter

is dangerous whenever the equipment

is connected to mains. Incorrect

installation of the motor or the frequency converter

may cause damage to the equipment, serious

personal injury or death.

Consequently, the instructions in this manual,

as well as national and local rules and safety

regulations, must be complied with.

■Safety regulations

1. The frequency converter must be disconnected

from mains if repair work is to be carried out. Check

that the mains supply has been disconnected

and that the necessary time has passed before

removing motor and mains plugs.

2. The [OFF/STOP] key on the control panel of

the frequency converter does n

ot disconnect

the equipment from mains and is thus n

ot to

be used as a safety switch.

3. Correct protective earthing of the equipment

must be established, the user must be protected

against supply voltage, and the motor must be

protected against overload in accordance with

applicable national and local regulations.

4. The earth leakage currents are higher than 3.5 mA.

5. Protection against motor overload is included in

the factory setting. Parameter 117, Motor thermal

protection default value is ETR trip 1.

ote: The function is initialised at 1.0 x rated

motor current and rated motor frequency (see

parameter 117, Motor thermal protection).

6. Do n

ot remove the plugs for the motor and mains

supply while the frequency converter is connected

to mains. Check that the mains supply has been

disconnected and that the necessary time has

passed before removing motor and mains plugs.

7. Reliable galvanic isolation (PELV) is not complied

with if the RFI switch is placed in OFF position.

This means that all control in - and outputs

can only be considered low-voltage terminals

withbasicgalvanicisolation.

8. Please note that the frequency converter has

more voltage inputs than L1, L2 and L3, when

the DC-bus terminals are used.

Check that a

ll voltage inputs have been

disconnected and that the necessary time has

passed before repair work is commenced.

■Warning against unintended start

1. The motor can be brought to a stop by

means of digital commands, bus commands,

references or a local stop, while the frequency

converter is connected to mains.

If personal safety considerations make it necessary

to ensure that no unintended start occurs, t

hese

stop functions are not sufficient.

2. While parameters are being changed, the

motor may start. Consequently, t

he stop key

[OFF/STOP] must always be activated, following

which data can be modified.

3. A motor that has been stopped may start if faults

occur in the electronics of the frequency converter,

or if a temporary overload or a fault in the supply

mains or the motor connection ceases.

175HA490.11

Warning:

Touching the electrical parts may be fatal - even after the equipment

has been disconnected from mains.

Using VLT

6002 - 6005, 200-240 V: Wait at least 4 minutes

Using VLT

6006 - 6062, 200-240 V: Wait at least 15 minutes

Using VLT

6002 - 6005, 380-460 V: Wait at least 4 minutes

Using VLT

6006 - 6072, 380-460 V: Wait at least 15 minutes

Using VLT 6102 - 6352, 380-460 V: Wait at least 20 minutes

Using VLT 6400 - 6550, 380-460 V: Wait at least 15 minutes

Using VLT

6002 - 6006, 525-600 V: Wait at least 4 minutes

Using VLT

6008 - 6027, 525-600 V: Wait at least 15 minutes

Using VLT

6032 - 6275, 525-600 V: Wait at least 30 minutes

MG.60.B9.02 - VLT is a registered Danfoss trademark

VLT

6000 HVAC Series

■Introduction to the Design Guide

This Design Guide is a tool intended to facilitate the sizing of systems in which VLT 6000 HVAC frequency

converters are used.

HVAC stands for Heating Ventilation Air-Conditioning.

This Design Guide progresses step-by-step through the different procedures required for selecting, installing

and programming a VLT 6000 HVAC.

The Design Guide forms part of the literature concept supplied with VLT 6000 HVAC. However, the Design

Guide is the most comprehensive document available.

When a VLT 6000 HVAC is supplied, it is accompanied by Operating Instruc tions and a Quick Setup Guide.

See the section Other Literature.

Operating Instructions: Describe how to ensure optimum mechanical and electrical installation,

and also deal with commissioning and service. The Operating Instructions

furthermore provide a description of the software parameters, thereby ensuring

thatyoucaneasilyfittheVLT6000HVACintoyourapplication.

Quick Setup Guide: Helps you get your VLT 6000 HVAC installed and commissioned quickly.

Design Guide: Used when designing systems with VLT 6000 HVAC. The Design Guide gives

all useful information about the VLT 6000 HVAC and HVAC systems. There is

a selection tool for you to choose the right VLT 6000 HVAC with the relevant

options and modules. The Design Guide hasexamplesofthemostcommon

types of HVAC applications. In addition, the Design Guide has all information

relating to Serial Communication.

This Design Guide is split in four sections that have information about VLT 6000 HVAC.

Introduction to HVAC: This section tells you the advantages that can be obtained by using frequency

converters in HVAC systems. Furthermore, you can read about the way a

frequency converter operates and about the advantages of the VLT 6000

HVAC, such as AEO - Automatic Energy Optimisation, RFI filter and other

HVAC-relevant functions.

There are also examples of applications and information is given about Danfoss

and CE-labelling.

The specification section deals with the requirements relating to bei

ng allowed

to supply and install frequency converters. This section can be used in

contract documents, whereby the total list of requirements relating to frequency

converters is determined.

The section ends with an Ordering Guide that makes it easier for y

ou to specify

and order a VLT 6000 HVAC.

MG.60.B9.02-VLTisaregisteredDanfosstrademark

VLT

6000 HVAC Series

Introduction to

HVAC

■Introduction to the Design Guide

Installation: This section shows you how to carry out correct mechanical installation

of a VLT 6000 HVAC.

In addition, the section has a description of how you ensure that the

installation of the VLT 6000 HVAC is EMC-correct. Furthermore, the section

includes a list of mains and motor connections, as well as a description of

control card terminals.

Programming: This section describes the control unit and the software parameters for the

VLT6000HVAC.ThereisalsoaguidetotheQuickSetupmenu,which

means that you will be able to start using your application very quickly.

All about VLT 6000: This section has information about status, warning and fault indications from

the VLT 6000 HVAC. In addition, the section has technical data, service

information, factory settings and information on special conditions.

NB!:

This symbol indicat

essomethingtobe

noted by the reader.

This symbol indicates a general warning.

This symbol indicates a high-voltage

warning.

MG.60.B9.02 - VLT is a registered Danfoss trademark

VLT

6000 HVAC Series

■Available literature

Below is a list of the literature available for VLT

6000 HVAC. It must be noted that there may be

deviations from one country to the next.

Please also refer to our web site http://drives.dan-

foss.com for information about new literature.

Supplied with the unit:

Operating instructions ....................................................................................................................... MG.60.AX.YY

Quick Setup ...................................................................................................................................... MG.60.CX.YY

Communication with VLT 6000 HVAC:

Software Dialog ................................................................................................................................ MG.50.EX.YY

Profibus Manual ................................................................................................................................ MG.10.LX.YY

Metasys N2 Manual .......................................................................................................................... MG.60.FX.YY

LonWorks Manual ............................................................................................................................. MG.60.EX.YY

Landis/Staefa Apogee FLN Manual ................................................................................................... MG.60.GX.YY

Modbus RTU Manual ........................................................................................................................ MG.10.SX.YY

DeviceNet Manual ............................................................................................................................. MG.50.HX.YY

Instructions for VLT 6000 HVAC:

LCP Remote Kit IP20 .......................................................................................................................... MI.56.AX.51

LCP Remote Kit IP54 .......................................................................................................................... MI.56.GX.52

LC-filter ............................................................................................................................................... MI.56.DX.51

IP20 terminal cover ............................................................................................................................. MI.56.CX.51

RCD instructions ................................................................................................................................. MI.66.AX.YY

Relay card instructions ........................................................................................................................ MI.66.BX.YY

Various literature for VLT 6000 HVAC:

Operating Instructions ....................................................................................................................... MG.60.AX.YY

Data sheet ........................................................................................................................................ MD.60.AX.YY

Installation Guide .............................................................................................................................. MG.56.AX.YY

VLT 6000 HVAC Cascade Controller ................................................................................................... MG.60.IX.YY

X = version number YY = language version

■Why use a frequency converter for controlling

fans and pumps?

A frequency converter takes advantage of the fact

that centrifugal fans and pumps follow the laws of

proportionality for such fans and pumps.

The graph below describes the laws of proportionality.

The graph shows that flow and pressure can be

regulated by changing the rpm figure.

■The clear advantage - energy savings

The very clear advantage of using a frequency

converter for controlling the speed of fans or pumps

lies in the electricity savings to be obtained.

When comparing with alternative regulating systems

and technologies, a frequency converter is the

optimum energy control system for regulating

fan and pump systems.

■Exampleofenergysavings

As can be seen from the figure (the laws of

proportionality), the flow is regulated by changing

the rpm figure. By reducing the speed only 20%

from the rated speed, the flow is also reduced by

20%.Thisisbecausetheflowisdirectlyproportional

MG.60.B9.02-VLTisaregisteredDanfosstrademark

VLT

6000 HVAC Series

Introduction to

HVAC

to the rpm figure. The consumption of electricity,

however, is reduced by 50%.

If the system in question only needs to be able to

supply a flow that corresponds to 100% a few days

in a year, while the average is below 80% of the

rated flow for the remainder of the year, the amount

of energy saved is even more than 50%.

The laws of proportionality

This figure describes the dependence of flow, pres-

sure and power consumption on the rpm figure.

Q=Flow P=Power

=Ratedflow P

=Ratedpower

= Reducing flow P

=Reducingpower

H = Pressure n = Speed regulation

= Rated pressure n

= Rated speed

= Reducing pressure n

= Reducing speed

MG.60.B9.02 - VLT is a registered Danfoss trademark

VLT

6000 HVAC Series

■Example with varying flow over 1 year

The example below is calculated on the basis of pump

characteristics obtained from a pump datasheet.

(45 kW). The same examples of calculations can be

used in the case of fan characteristics.

The result obtained is savings in excees of 50% at the

given flow distribution over a year, corresponding

to 8,760 hours.

Typically, the example calculated below results in a

pay-back period of one year - depending on the price

per kWh and the price of the frequency converter.

Pump characteristics

Energy savings

This figure compares flow regulation via valves and

without speed control with flow regulation via a

frequency converter.

shaft

shaft output

Flow distribution over 1 year

m3/t Distribution Valve regulation Frequency converter control

% Hours Power Consumption Power Consumption

-B

kWh A

-C

kWh

350 5 438 42,5 18.615 42,5 18.615

300 15 1314 38,5 50.589 29,0 38.106

250 20 1752 35,0 61.320 18,5 32.412

200 20 1752 31,5 55.188 10,0 17.520

150 20 1752 28,0 49.056 6,5 11.388

100 20 1752 23,0 40.296 3,5 6.132

100 8760 275.064 124.173

MG.60.B9.02-VLTisaregisteredDanfosstrademark

VLT

6000 HVAC Series

Introduction to

HVAC

■Better regulation

If a frequency converter is used for regulating the

flow or pressure of a system, improved regulation is

obtained which can be adjusted very precisely.

A frequency converter can vary the speed of the

fan or pump infinitely, thereby obtaining infinitely

variable control of flow and pressure.

Furthermore, a frequency converter can quickly

regulate the speed of the fan or pump, so as to adapt it

to new flow or pressure conditions in the system.

More traditional, mechanical flow or pressure regulating

systems tend to provide slow, inaccurate regulation if

compared with that of the frequency converter.

■Frequency converters generate less noise

If the speed of a fan is changed, the sound level

changes, too. If the rpm figure is reduced by

50% from the rated rpm value, the sound level

will go down by approx. 16 dB(A).

The formula is:

■Simpler installation when using a fre-

quency converter

A frequency converter can replace a traditional

regulating system, in which mechanical dampers and

valves are used for regulating flow or pressure.

The great advantage involved in using a frequency

converter is that the system becomes simpler,

since a lot of the mechanical and electrical

equipment is no longer required.

■V-belts no longer required

In mechanical regulating systems, where the fan

is driven by V-belts, it is necessary to change belt

pulleys in order to adjust the fan speed to match

the necessary maximum load. Using a frequency

converter, the V-belts can be replaced by directly

driven motors, whose speed is changed simply

by means of the frequency converter.

The efficiency of the system improves and the entire

installation takes up less space. There is no dust

from the V-belt and less maintenance.

■Regulating dampers and valves no longer required

Since the flow or pressure can be regulated by means

of the frequency converter, no regulating dampers

and valves are required in the system.

■Cos ϕ compensation

Generally speaking, a frequency converter with a cos

of 1 provides power factor correction for the cos ϕ

of the motor, which means that there is no need to

makeallowanceforthecosϕ of the motor when

sizing the power factor correction unit.

■Star/delta starter or soft-starter not required

When larger motors are started, it is necessary in many

countries to use equipment that limits the start-up

current. In more traditional systems, a star/delta starter

or soft-starter is widely used. Such motor starters are

not required if a frequency converter is used.

As illustrated in the figure below, a frequency converter

does not consume more than rated current.

1=VLT6000HVAC

2 = Star/delta starter

3=Soft-starter

4 = Start directly on mains

■Cost of using frequency converter not higher

The example on the following page shows that a

lot of equipment is not required when a frequency

converter is used. It is possible to calculate the

cost of installing the two different systems. In the

example on the following page, the two systems can

be established at roughly the same price.

MG.60.B9.02 - VLT is a registered Danfoss trademark

VLT

6000 HVAC Series

■Without a frequency converter

Thefigureshowsafansystemmadeinthetraditionalway. D.D.C. = DirectDigitalControl

E.M.S. = Energy Management

System

V.A.V. = Variable Air Volume

Sensor P = Pressure

Sensor T = Temperature

■With a frequency converter

he figure shows a fan system controlled by VLT 6000 HVAC frequency converters.

MG.60.B9.02-VLTisaregisteredDanfosstrademark

VLT

6000 HVAC Series

Introduction to

HVAC

■Control principle

A frequency converter rectifies AC voltage from

mains into DC voltage, after which this DC

voltage is converted into a AC current with a

variable amplitude and frequency.

The motor is thus supplied with variable voltage and

frequency, which enables infinitely variable speed

control of three-phased, standard AC motors.

1. Mains voltage

3 x 200 - 240 V AC, 50 / 60 Hz.

3 x 380 - 460 V AC, 50 / 60 Hz.

3 x 525 - 600 V AC, 50 / 60 Hz.

. Rectifier

A three-phase rectifier bridge that rectifies AC

current into DC current.

. Intermediate circuit

DC voltage = 1.35 x mains voltage [V].

. Intermediate circuit coils

Even out the intermediate circuit voltage and reduce

the harmonic current feedback to the mai

ns supply.

. Intermediate circuit capacitors

Even out the intermediate circuit voltage.

. Inverter

Converts DC voltage into variable AC voltage

withavariablefrequency.

. Motor voltage

Variable AC voltage, 0-100% of mains supply voltage.

. Control card

This is where to find the computer that controls

the inverter which generates the pulse pattern by

which the DC voltage is converted into variable

AC voltage with a variable frequency.

MG.60.B9.02 - VLT is a registered Danfoss trademark

VLT

6000 HVAC Series

■CE labelling

What is CE labelling?

The purpose of CE labelling is to avoid technical

obstacles to trade within EFTA and the EU. The

EU has introduced the CE label as a simple way of

showing whether a product complies with the relevant

EU directives. The CE label says nothing about the

specifications or quality of the product. Frequency

converters are regulated by three EU directives:

The machinery directive (98/37/EEC)

All machines with critical moving parts are covered

by the machinery directive, which came into force

on 1 January 1995. Since a frequency converter is

largely electrical, it does not fall under the machinery

directive. However, if a frequency converter is supplied

for use in a machine, we provide information on safety

aspects relating to the frequency converter. We do

this by means of a manufacturer’sdeclaration.

The low-voltage directive (73/23/EEC)

Frequency converters must be CE labelled in

accordance with the low-voltage directive, which came

into force on 1 January 1997. The directive applies to

all electrical equipment and appliances used in the 50 -

1000 Volt AC and the 75 - 1500 Volt DC voltage ranges.

Danfoss CE labels in accordance with the directive and

issues a declaration of conformity upon request.

The EMC directive (89/336/EEC)

EMC is short for electromagnetic compatibility. The

presence of electromagnetic compatibility means

that the mutual interference between different

components/appliances is so small that the functioning

of the appliances is not affected.

The EMC directive came into force on 1 January 1996.

Danfoss CE labels in accordance with the directive and

issues a declaration of conformity upon request. In

order that EMC-correct installation can be carried out,

this manual gives detailed instructions for installation. In

addition, we specify the standards which our different

products comply with. We offer the filters that can be

seen from the specifications and provide other types of

assistance to ensure the optimum EMC result.

In the great majority of cases, the frequency converter

is used by professionals of the trade as a complex

component forming part of a larger appliance, system

orinstallation.Itmustbenotedthattheresponsibility

for the final EMC properties of the appliance, system

or installation rests with the installer.

NOTE: 525-600 V units are not CE labelled.

■Application examples

The next few pages give typical examples of

applications within HVAC.

If you would like to receive further information

about a given application, please ask your Danfoss

supplier for an information sheet that gives a full

description of the application.

Ask for The Drive to...Improving Variable Air Volume Vent ilation systems MN.60.A1.02

Ask for The Drive to...Improving Constant Air Volume Ve ntilation systems MN.60.B1.02

Ask for The Drive to...Improving fan control o n cooling towers MN.60.C1.02

Ask for The Drive to...Improving condenser water pumping systems MN.60.F1.02

Ask for The D rive to...Improve your primary p um ping in primay/secondar y pumping systems MN.60.D1.02

Ask for The Drive to...Improve your secondary pumping in primay/secondary pum ping systems MN.60.E1.02

MG.60.B9.02-VLTisaregisteredDanfosstrademark

VLT

6000 HVAC Series

Introduction to

HVAC

■Variable Air Volume

VAV or Variable Air Volume systems, are used to

control both the ventilation and temperature to

satisfy the requirements of a building. Central VAV

systems are considered to be the most energy efficient

method to air condition buildings. By designing

central systems instead of distributed systems, a

greater efficiency can be obtained.

The efficiency comes from utilizing larger fans and

larger chillers which have much higher efficiencies

than small motors and distributed air-cooled

chillers. Savings are also seen from the decreased

maintenance requirements.

■The new standard

While dampers and IGVs work to maintain a

constant pressure in the ductwork, a frequency

converter solution saves much more energy and

reduces the complexity of the installation. Instead

of creating an artificial pressure drop or causing a

decrease in fan efficiency, the frequency converter

decreases the speed of the fan to provide the flow

and pressure required by the system.

Centrifugal devices such as fans behave according

to the centrifugal laws. This means the fans

decrease the pressure and flow they produce as

their speed is reduced. Their power consumption

is thereby significantly reduced.

The return fan is frequently controlled to maintain a fixed

difference in airflow between the supply and return. The

advanced PID controller of the VLT 6000 HVAC can be

used to eliminate the need for additional controllers.

Pressure

signal

VAV boxes

Flow

Cooling coil

Heating coil

Filter

Pressure

transmitter

Supply fan

Return fan

MG.60.B9.02 - VLT is a registered Danfoss trademark

VLT

6000 HVAC Series

■Constant Air Volume

CAV, or Constant Air Volume systems are central

ventilation systems usually used to supply large

common zones with the minimum amounts of fresh

tempered air. They preceded VAV systems and

therefore are found in older multi-zoned commercial

buildings as well. These systems preheat amounts

of fresh air utilizing Air Handling Units (AHUs) with a

heating coil, and many are also used to air condition

buildings and have a cooling coil. Fan coil units are

frequently used to assist in the heating and cooling

requirements in the individual zones.

■The new standard

With a frequency converter, significant energy savings

can be obtained while maintaining decent control of the

building. Temperature sensors or CO2 sensors can

be used as feedback signals to frequency converters.

Whether controlling temperature, air quality, or both, a

CAV system can be controlled to operate based on

actual building conditions. As the number of people

in the controlled area decreases, the need for fresh

air decreases. The CO2 sensor detects lower levels

and decreases the supply fans speed. The return fan

modulates to maintain a static pressure setpoint or

fixed difference between the supply and return air flows.

With temperature control, especially used in air

conditioning systems, as the outside temperature

varies as well as the number of people in the controlled

zone changes, different cooling requirements exist.

As the temperature decreases below the set-point,

the supply fan can decrease its speed. The return fan

modulates to maintain a static pressure set-point. By

decreasing the air flow, energy used to heat or cool the

fresh air is also reduced, adding further savings.

Several features of Danfoss HVAC dedicated frequency

converter, the VLT 6000 HVAC can be utilized to

improve the performance of your CAV system. One

concern of controlling a ventilation system is poor

air quality. The programmable minimum frequency

can be set to maintain a minimum amount of supply

air regardless of the feedback or reference signal.

The frequency converter also includes a two zone, 2

setpoint PID controller which allows monitoring both

temperature and air quality. Even if the temperature

requirement is satisfied, the drive will maintain enough

supply air to satisfy the air quality sensor. The

controller is capable of monitoring and comparing

two feedback signals to control the return fan by

maintaining a fixed differential air flow between

the supply and return ducts as well.

Pressure

signal

Cooling coil

Heating coil

Filter

Pressure

transmitter

Supply fan

Return fan

Temperature

signal

Temperature

transmitter

MG.60.B9.02-VLTisaregisteredDanfosstrademark

VLT

6000 HVAC Series

Introduction to

HVAC

■Cooling Tower Fan

Cooling Tower Fans are used to cool condenser water

in water cooled chiller systems. Water cooled chillers

provide the most efficient means of creating chilled

water. They are as much as 20% more efficient than

air cooled chillers. Depending on climate, Cooling

towers are often the most energy efficient method of

cooling the condenser water from chillers.

They cool the condenser water by evaporation.

The condenser water is sprayed into the cooling

tower onto the cooling towers "fill" to increase its

surface area. The tower fan blows air through the

fill and sprayed water to aid in the evaporation.

Evaporation removes energy from the water dropping

its tempera-ture. The cooled water collects in the

cooling towers basin where it is pumped back into the

chillers con-denser and the cycle is repeated.

■The new standard

With a frequency converter, the cooling towers fans

can be controlled to the required speed to maintain the

condenser water temperature.T frequency converters

can also be used to turn the fan on and off as needed.

Several features of Danfoss HVAC dedicated drive,

the VLT 6000 HVAC can be utilized to improve the

performance of your cooling tower fans application.

As the cooling tower fans drop below a certain

speed, the effect the fan has on cooling the water

becomes small. Also, when utilizing a gear-box

to frequency converter the tower fan, a minimum

speed of 40-50% may be required.

The customer programmable minimum frequency

set-ting of the is available to maintain this

minimum frequency even as the feedback or speed

reference calls for lower speeds.

Also as a standard feature, you can program the

frequency converter to enter a "sleep" mode and stop

the fan until a higher speed is required. Additionally,

some cooling tower fans have undesireable frequencies

that may cause vibrations. These frequencies can

easily be avoided by programming the bypass

frequency ranges in the frequency converter.

Water Inlet

Water Outlet

CHILLER

Temperature

Sensor

BASIN

Conderser

Water pump

Supply

MG.60.B9.02 - VLT is a registered Danfoss trademark

VLT

6000 HVAC Series

■Condenser pumps

Condenser Water pumps are primarily used to

circulate water through the condenser section of

water cooled chillers and their associated cooling

tower. The condenser water absorbs the heat from

the chillers condenser section and releases it into

the atmosphere in the cooling tower. These systems

areusedtoprovidethemostefficientmeansof

creating chilled water, they are as much as 20%

more efficient than air cooled chillers.

■The new standard

Frequency converters can be added to condenser

water pumps instead of balancing the pumps with a

throttling valve, to control the water temperature instead

of tower fans, or to control the water temperature

in addition to controlling the tower fans.

Using a frequency converter instead of a throttling

valve simply saves the energy that would have been

absorbed by the valve. This can amount to savings

of 15-20% or more. Frequency converters are used

to control the water temperature instead of controlling

the cooling tower fans when it is more convenient to

access the pumps than the tower fans. Pump control

is used in conjunction with fan control to control the

water temperature in free cooling applications or when

the cooling towers are significantly oversized. In some

circumstances the environment itself causes the water

to become too cool even when the fan is off. The

frequency converter controlled pump maintains the

appropriate temperature by increasing or decreasing

the discharge pressure and flow rate. The decreased

pressure at the spray nozzle in the cooling tower

decreases the surface area of the water exposed to the

air. Cooling is decreases and the design temperature

can be maintained in periods of low loads.

Water Inlet

Water Outlet

CHILLER

BASIN

Conderser

Water pump

Supply

Temperature

sensor

MG.60.B9.02-VLTisaregisteredDanfosstrademark

VLT

6000 HVAC Series

Introduction to

HVAC

■Primary pumps

Primary pumps in a primary/secondary pumping

system can be used to maintain a constant flow

through devices that encounter operation or control

difficulties when exposed to variable flow. The primary/

secondary pumping technique decouples the "primary"

production loop from the "secondary" distribution

loop. Thisallowsdevicessuchaschillerstoobtain

constant design flow and operate properly while

allowing the rest of the system to vary in flow.

As the evaporator flow rate decreases in a chiller, the

chilled water begins to become over-chilled. As this

happens, the chiller attempts to decrease its cooling

capacity. If the flow rate drops far enough, or too

quickly, the chiller cannot shed its load sufficiently and

the chiller’s low evaporator temperature safety trips

the chiller requiring a manual reset. This situation is

common in large installations especially when two

or more chillers in parallel are installed if primary/

secondary pumping is not utilized.

■The new standard

Depending on the size of the system and the size

of the primary loop, the energy consumption of the

primary loop can become substantial.

A frequency converter can be added to the primary

system, to replace the throttling valve and/or trimming

of the impellers, leading to reduced operating

expenses. Two control methods are common:

The first method uses a flow meter. Because the

desired flow rate is known and is constant, a flow meter

can be installed at the discharge of each chiller can be

used to control the pump directly. Using the built-in

PID controller, the frequency converter will always

maintain the appropriate flow rate, even compensating

for the changing resistance in the primary piping loop

as chillers and their pumps are staged on and off.

The other method is local speed determination. The

operator simple decreases the output frequency

until the design flow rate is achieved.

Using a frequency converter to decrease the pumps

speed is very similar to trimming the pumps impeller,

exceptitdoesn’t require any labor and the pumps

efficiency remains higher. The balancing contractor

simply decreases the speed of the pump until the

proper flow rate is achieved and leaves the speed

fixed. The pump will operate at this speed any time the

chiller is staged on. Because the primary loop doesn’t

have control valves or other devices that can cause

the system curve to change and the variance due to

staging pumps and chillers on and off is usually small,

this fixed speed will remain appropriate. In the event

the flow rate needs to be increased later in the systems

life, the frequency converter can simply increase the

pumps speed instead of requiring a new pump impeller.

CHILLER

Flowmeter

MG.60.B9.02 - VLT is a registered Danfoss trademark

VLT

6000 HVAC Series

■Secondary pumps

Secondary pumps in a primary/secondary chilled

water pumping system are used to distribute the

chilled water to the loads from the primary production

loop. The primary/secondary pumping system is

used to hydronically decouple one piping loop from

another. In this case. The primary pump is used

to maintain a constant flow through the chillers

while allowing the secondary pumps to vary in flow,

increase control and save energy.

If the primary/secondary design concept is not used

and a variable volume system is designed, when

theflowratedropsfarenoughortooquickly,the

chiller cannot shed its load properly. The chiller’s

low evaporator temperature safety then trips the

chiller requiring a manual reset. This situation is

common in large installations especially when two

or more chillers in parallel are installed.

■The new standard

While the primary-secondary system with two-way

valves improves energy savings and eases system

control problems, the true energy savings and control

potential is realized by adding frequency converters.

With the proper sensor location, the addition

of frequency converters allows the pumps to

vary their speed to follow the system curve

instead of the pump curve.

This results in the elimination of wasted energy

and eliminates most of the over-pressurization the

two-way valves can be subjected too.

As the monitored loads are satisfied, the loads two-way

valves close down. This increases the differential

pressure measured across the load and two-way

valve. As this differential pressure starts to rise, the

pump is slowed to maintain the control head also

called setpoint value. This setpoint value is calculated

by summing the pressure drop of the load and two

way valve together under design conditions.

NB!:

Please note that when running multiple

pumps in parallel, they must run at the

same speed to maximize energy savings,

either with individual dedicated drives or one drive

running multiple pumps in parallel.

CHILLER

∆P

MG.60.B9.02-VLTisaregisteredDanfosstrademark

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Danfoss VLT® 6000 HVAC User guide

Danfoss VLT® 6000 HVAC User guide

Danfoss VLT® 6000 HVAC User guide

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