Appendices
Appendix J - Core Measurement Parameters: Power Factor
112
Building Technologies
125-202
06/06/2017
Measurement Parameters: Power
BACnet
Object
Identifier
Modbus
Register
Modbus
Offset
(Offset to a
Base of 40001)
kVA – Apparent Power defined as Kilo Volt-Amperes
is the product of the RMS volts across a load or source times the RMS current passing through the load or source divided by 1000. This is the
square root of the sum of the squares of the KW and the KVAR. But knowing just the KVA, you do not know what part is KW and what part is
KVAR. However, it is easy to measure with a power meter. The phase angle between the voltage wave and the current wave is somewhere
between ± 90 degrees.
System Maximum Instantaneous Apparent Power Demand
(kVA Demand System Max) - resettable
returns maximum demand value read since startup or reset of demand register
= kVA Dmd max, unsigned, absolute, kVA demand, in kVA, BACnet
= kVA Dmd max value, unsigned, absolute, kVA demand, in kVA
= positive kVA Dmd max, unsigned, positive value, kVA demand, in kVA
= negative kVA Dmd max, unsigned, negative value, kVA demand, in kVA
NOTES:
If Dmd value>0, Dmd positive = Dmd value, Dmd negative = 0
If Dmd value<0, Dmd negative = Dmd value, Dmd positive = 0
8040
‒
‒
‒
‒
44082
46082
47082
‒
4081
6081
7081
System Average Apparent Power Demand
(kVA Demand System Now) - resettable
returns new value every minute, will compare and post to min/max registers
= kVA Dmd now, unsigned, absolute, most recent dmd window, in kVA, BN
= kVA Dmd now value, unsigned, kVA power, most recent dmd win, kVA
= positive kVA Dmd now, unsigned, kVA power, most recent dmd win, kVA
= negative kVA Dmd now, unsigned, kVA power, most recent dmd win, kVA
NOTES:
If Dmd value>0, Dmd positive = Dmd value, Dmd negative = 0
If Dmd value<0, Dmd negative = Dmd value, Dmd positive = 0
8050
‒
‒
‒
‒
44083
46083
47083
‒
4082
6082
7082
System Total Apparent Power (kVA System)
equals unsigned value of ABS(kVA L1)+ABS(kVA L2)+ABS(kVA L3), in kVA
= kVA Sys, signed, absolute, in kW, BACnet
= kVA Sys value, unsigned, total instantaneous true power, in kVA
= positive kVA Sys, unsigned, positive instantaneous true power, in kVA
= negative kVA Sys, unsigned, negative instantaneous true power, in kVA
NOTES:
If kVA sys value>0, kVA sys positive = kVA sys, kVA sys negative = 0
If kVA sys value<0, kVA sys negative = kVA sys, kVA sys positive = 0
8000
‒
‒
‒
‒
44013
46013
47013
‒
4012
6012
7012
System Net Total Apparent Power (kVA System Net)
equals signed net value of ABS(kVA L1)+ABS(kVA L2)+ABS(kVA L3), in kVA
= kVA SysNet, signed, absolute, in kW, BACnet
8001
‒
‒
Individual Phase Apparent Power- L1 (kVA L1)
= total kVA L1 value, signed, individual L1 phase true power in kVA, BACnet
= total kVA L1 value, unsigned, individual L2 phase true power, in kVA
= positive kVA L1 value, unsigned, individual L2 phase true power, in kVA
= negative kVA L1 value, unsigned, individual L2 phase true power, in kVA
NOTES:
If kVA L1 value>0, positive kVA L1= total kVA L1, negative kVA L1= 0
If kVA L1 value<0, negative kVA L1= total kVA L1, positive kVA L1= 0
8010
‒
‒
‒
‒
44047
46047
47047
‒
4046
6046
7046
Individual Phase Apparent Power- L2 (kVA L2)
= total kVA L2 value, signed, individual L2 phase true power in kVA, BACnet
= total kVA L2 value, unsigned, individual L2 phase true power, in kVA
= positive kVA L2 value, unsigned, individual L2 phase true power, in kVA
= negative kVA L2 value, unsigned, individual L2 phase true power, in kVA
NOTES:
8020
‒
‒
‒
‒
44048
46048
47048
‒
4047
6047
7047