1. Variable Frequency Drives Bypass Options

2. Mechanically Interlocked
VFD Bypass Operation
Two Contactor Bypass
Power Supply
SED2
Drive
Mechanically Interlocked
Drive Output Contactor
The Eco has been designed and is tailor-made by Siemens exclusively for HVAC applications.
Family of Variable Speed Drives with common:
software
hardware layout
user interface Fan & Pump Motors have variable torque-speed characteristics
torque is proportional to the square of the speed, T=k x (rpm)2
this means a small low speed load torque
and a large high speed load torque.
load inertia (especially large fans) can be quite high so getting up to setpoint speed may take a few more seconds User Benefits of Variable Speed Drives
overall energy and cost savings along with improved comfort levels through better regulation.
Bypass Contactor
Motor 1

3. Mechanically Interlocked
VFD Bypass Operation
Three Contactor Bypass
Power Supply
Optional Input Contactor
SED2
Drive
Mechanically Interlocked
Drive Output Contactor
The Eco has been designed and is tailor-made by Siemens exclusively for HVAC applications.
Family of Variable Speed Drives with common:
software
hardware layout
user interface Fan & Pump Motors have variable torque-speed characteristics
torque is proportional to the square of the speed, T=k x (rpm)2
this means a small low speed load torque
and a large high speed load torque.
load inertia (especially large fans) can be quite high so getting up to setpoint speed may take a few more seconds User Benefits of Variable Speed Drives
overall energy and cost savings along with improved comfort levels through better regulation.
Bypass Contactor
Motor
Optional “3rd” drive input contactor electrically isolates the VFD 1

4. Bypass Types – Conventional and Electronic
Conventional bypass – uses hard- wired electrical components for mechanical bypass control
Switches
Fuses
Relays
Electronic bypass – electronic logic control with simple keypad
Reduced wiring and mechanical components
Improved system reliability
Additional logic features standard
Interlocked Start
2 Safety circuits
Smoke Purge logic
Conventional Bypass
Electronic Bypass

5. SED2 Conventional Bypass
VFD and Bypass cabinet mounted on common back plate
Conventional electromechanical control
Indicating lights, selector switches, relays
All voltages and HP ratings
Configurations available:
Disconnect (fused on non- fused)
NEMA 1 cabinet
2 or 3 contactor control
manual/auto bypass selection standard
line/load reactor option
Damper end-switch logic option

6. Conventional Bypass Components
Protective cover
Gland Plate
Conduit Connector
Mounting Back Plate
Bypass ON Indicator Light
Drive /Off / Bypass Selector
Line Disconnect
Drive Test Selector (3 contactor only)

7. Conventional Bypass Components
Line reactor (optional)
Control transformer
Input contactor (optional)
Control relays
Power fuses (optional)
Output contactor
Line disconnect
Bypass contactor
Motor overload relay
Field wiring terminals

8. Conventional Bypass Power Range
A-F denotes VFD frame size
For more info, see the Bypass menu on this CD

9. Electronic Bypass Features
Easy-touch keypad with status display
Common remote start/stop
Auto bypass
Essential service mode
Interlock start logic
Disconnect options
Disconnect
Fused Disconnect
Circuit Breaker
Two and three contactor models
6 digital inputs and 6 digital outputs
Optional line or load reactor

10. Electronic Bypass Components
Electronic control board
Input contactor (optional)
Field wiring terminals
Line reactor (optional)
Power fuses (optional)
Control transformer
Line disconnect
Output contactor
Bypass contactor
Motor overload relay

11. Electronic Bypass Keypad
Easy-touch electronic keypad displays status and operating configuration
Indicates current status with LEDs
Built -in logic reduces wiring and ensures safe operation

12. Electronic Bypass Keypad Features
Indicates that input contactor is closed and drive has power.
Indicates input contactor is closed when on, close pending when flashing.
Toggling this button opens / closes the input contactor.
Enables hand bypass mode.
Enable remote bypass. Bypass light w/ flash. Contactor closes and light comes on when Remote Start input closes.
Enable closes both drive input and output contactors.
Essential service light flashes when this feature is activated.
Auto Bypass light flashes when this feature is activated.
Disconnect the motor whether in drive or bypass mode.
Indicates that one of the safety inputs is open.
Indicates that either the overload input has closed or that the thermal overload has tripped.
Indicates present operational state of interlocked start logic.

13. For more info, see the Bypass menu on this CD
Electronic Bypass Power Range
A-F denotes VFD frame size
For more info, see the Bypass menu on this CD

14. Siemens SED2 VFD Advantages
Low harmonics design
Small enclosure size
Many standard features
Reduces operating cost
Low power losses/high efficiency
Minimal effect on customer power
Wide power range – from ½ to 125 HP