7154 VFD Presentation #5 June 2002 Paul Weingartner

Application of VFDs

VFDs applied for energy savings mation/features/BNP__Features__Item/0, 1338,73944,00.html mation/features/BNP__Features__Item/0, 1338,73944,00.html In the hvac industry, vfd’s are usually found on motors that drive fans, blowers, pumps, cooling towers, etc. The Department of Energy reports that 64% of all electrical energy in the U.S. is consumed by electric motors.

Typical energy savings According to some studies, the addition of vfd’s to an existing system can result in a reduction in energy consumption of 30% to 60%. ASHRAE Standard 90.1 will effectively require vfd’s on every hvac motor except the smallest ones in commercial buildings of more than 25,000 sq ft.

Water pumping example With a 25hp motor running 23 hours per day (2 hours at 100 percent speed; 8 hours at 75 percent; 8 hours at 67 percent; 5 hours at 50 percent, which is typical of the water supply industry) a VFD can reduce energy use by 45 percent.At 10 cents/ kWh, this results in an annual savings of $5,374. Source: CEC, sys/Water_Pump_Bro.pdf

Comparison of valve vs. VFD pump

Observation If the rate of electricity is $0.02 per KWHr, the chances are slim that you’ll be able to cost justify a Variable Frequency Drive for your system. However, if the electricity rate is $0.05 per KWHr or higher, you can expect to show fast paybacks for virtually any system.

How is the current system being used The Duty Cycle of your system (where the system operates and for how long) will also affect potential savings. If, for instance, the system tends to operate close to the Design Point for the majority of the time, the savings potential through speed control is limited. On the other hand, if the system is operating at reduced flows for extended periods of time, the potential savings by using VFD’s is great. The Duty Cycle of your system (where the system operates and for how long) will also affect potential savings. If, for instance, the system tends to operate close to the Design Point for the majority of the time, the savings potential through speed control is limited. On the other hand, if the system is operating at reduced flows for extended periods of time, the potential savings by using VFD’s is great

Cost savings table

Centrifugal pump

Money A penny saved in NOT equal to a penny earned!! For commercial businesses, a penny saved is equal to 20 pennies earned (revenue) because the net income approximates to 5% of the revenue. m m m m

Payback Not this kind of Payback

Payback

Using energy eff motor S = x HP x C x N [ 100/SE - 100/PE ] S = Energy Savings per 100% load C = Energy Costs $ per kilowatt hour (KWH) N = Hours per year running time SE = Standard efficiency product at full load PE = Premium efficiency product at full load

Device Net Standards based protocol Must supply external 24VDC to network Typical devices VFD VFD PLC PLC Displays Displays Push buttons Push buttons Photoeyes Photoeyes Motor starters Motor starters

Devices Each device on the network is a “node” Max of 64 nodes (0-63) Each device must be “commisioned” before use. The default address is 63 and should be changed in configuration The default address is 63 and should be changed in configuration Each node must be unique Can’t have two nodes both with the same address Can’t have two nodes both with the same address

RS Networx With RSNetWorx Software for DeviceNet Network you can: Define the devices that are present on your network. You can either manually drag/drop devices/modules or go online to a DeviceNet network and let the software determine the devices/modules that are present. Define configuration settings for devices on the DeviceNet network through a convenient property page interface. Define the input/output information exchanges that you want to take place on the DeviceNet network.

DeviceNet features Low Cost (Based on low cost CAN chip). High Speed. It supports 3 baud rates: 125Kbps, 250Kbps and 500 Kbps which is believed to meet 95% of the industrial requirement. Reliable. It uses the well proven CAN protocol incinerates with the application layers that has undergone strict conformance testing to ensure the reliability. Support up to 64 active nodes. In theory, the node can be expended by using bridge system (such as CAN/CAN bridge or other gateway). Easy installation. Virtually "Plug-and-Play"

Cable lengths

PLC DeviceNet Accomplished with a DeviceNet Scanner card 1747-SDN (for SLC500 family) Plugs into standard slot Takes 32 words of memory 1 word = 16 bits = 2 bytes 1 word = 16 bits = 2 bytes

PLC SDN module display Shows both error codes and current operating info Code 92 = no power Code 80 = idle mode Will show its node address

Communication Using a tool such as RS Networx, each device must be given: Node address Node address Told whether it is a master or a slave device Told whether it is a master or a slave device Told what info to share and who to share it with Told what info to share and who to share it with

DeviceNet settings Node address Baud rate (125, 250, 500kb/sec) Master/slave Channel data Destination node address Masking (* careful on Powerflex drives)

Troubleshooting Always, without exception cycle power on all devices after configuration changes in networked systems

Troubleshooting 2 Look for the error codes Always backup and grab baseline data before making changes Check LED status indicators

PLC SDN example PLC addressing O: is the file O: is the file O:2 is the slot O:2 is the slot O:2.1 is the word O:2.1 is the word O:2.1/5 is the bit O:2.1/5 is the bit Numbering starts at zero

Example If the SDN module is in slot 2 of the PLC O:2.0/0 is the run bit for the DeviceNet module O:2.0/0 is the run bit for the DeviceNet module O:2.1 is the Command word O:2.1 is the Command word I:2.1 is the Status word I:2.1 is the Status word

Command word (bit – function) 0= Stop 1= Start 4= Direction

Status word (bit – function) 0 = Ready 2 = Command direction 3 = Actual direction 4= Accelerating (1=yes) 5 = Deaccelerating (1=yes) 6 = Alarm 7 = Fault

Powerflex DeviceNet By default 2 words are passed back Status word Status word Speed setting Speed setting Can be configured to send back any parameter of interest Parameters are referenced starting above #379 (the last Powerflex parameter)

Simple program

Tools needed for DeviceNet systems RS Networx for DeviceNET Careful – they sell another version for Control Logix Careful – they sell another version for Control Logix Protocol converter or protocol gateway PC RS Linx (Lite will work)

RS Linx Communication gateway for RS software and the PLC, VFD, Displays You have to see the devices on the net with RS Linx first. Else….

RS Linx versions Lite – ships with PLC software OEM, Gateway – can be used to connect to Active-X compliant systems

What can you do with this stuff WebExcel

RS Drive Tools Ability to backup configuration of drives Clone drive setups Advanced tools – analysis Not for average user Not for average user