Appendix: Earth Grounding; Comfortpoint Open And Selv; Comfortpoint Open And En60204-1; Functional Emc Grounding - Honeywell ComfortPoint Open CPO-PC400-W Manual

CPO-PC400-W/CPO-PC400-UW HVAC CONTROLLER
APPENDIX: EARTH
GROUNDING

ComfortPoint Open and SELV

In order to avoid distribution of noise or earth ground
potential differences over networks or other connections,
the CPO-PC400-W/CPO-PC400-UW is designed to comply
with SELV (Safety Extra Low Voltage).
Furthermore, SELV offers the greatest possible safety
against electrical impact.
To support SELV, all Honeywell external (CRT series) or
internal transformers comply with standard EN60742.
Earth grounding is therefore not recommended.

ComfortPoint Open and EN60204-1

However, if compliance with the standard EN60204-1 is
required, note the following:
General Information about EN60204-1
EN60204-1 defines electrical safety for a complete
application/machine including controllers, sensors,
actuators and any connected/controlled electrical device.
EN60204-1 requires controllers to be powered by PELV
(Protective Extra-Low Voltage) and earth grounding of the
secondary side of the used transformers or earth
grounding of the system ground.
Fig. 27. Connecting and earth grounding multiple CPO-PC400-W/CPO-PC400-UW HVAC Controllers (single
NOTES:
— Use a noise-free earth ground inside the cabi-
net.
— Use one star-point to split power for controllers
and field devices.
— If the transformer is used for several controllers,
each controller ground has to be wired sepa-
rately to the star point.
EN0B-0085 IE10 R0420
110VAC/230VAC
24VAC
F1
CPO-PC400-W/
CPO-PC400-UW
Earth grounding is prescribed to prevent the unexpected
start-up of connected rotating/moving machines due to an
insulation fault and double earth grounding somewhere in
the plant.
The use of an earth leakage monitor is also possible to
fulfill PELV if earth grounding is prohibited.
When is EN60204-1 Applicable to
ComfortPoint Open?
SAFETY AGAINST ELECTRICAL IMPACT
EN60204-1 is not mandatory; this is because electrical
safety is provided by the use of SELV and transformers
according to standard EN60742.
SAFETY AGAINST UNEXPECTED START-UP OF
ROTATING/MOVING MACHINES
If the application/plant does not contain machines that
can be harmful to the operator due to an unexpected start-
up, the standard EN60204-1 is not applicable. If such
machines are encountered, then EN60204-1 must be
followed. Grounding is required.

Functional EMC Grounding

• Use a cable as short as possible for grounding:
2
min 1.5 mm (16 AWG).
• For connection details, refer to the following example.
EXAMPLE
Connecting a single transformer with multiple CPO-
PC400-W/CPO-PC400-UW HVAC Controllers earth-
grounded as per EN60204-1.
• Connect earth ground to terminal 2 of the CPO-PC400-
W/CPO-PC400-UW HVAC Controllers.
Func on Earth
Grounding for EMC
CPO-PC400-W/
CPO-PC400-UW
transformer)
— If a field device that prohibits earth grounding
is connected to the system ground, an isolation
monitoring device must be used instead of
earth grounding.
— If the field device transformer is physically far
away from the controller, earth grounding must
still be performed for the controller.
38
Func on Earth
Grounding for EMC