HSP GmbH Zum Handwerkerhof 2 90530 Wendelstein Tel. 09129 / 2852-0 Fax: 09129 / 2852-11 Web: www.hsshsp.de EMAIL: [email protected]
NTG-3000 Operating Instructions Version 2.11
Page 14 of 18
13
Algorithms
The
NTG-3000
is equipped with various algorithms to catch errors and to detect and to
display them.
13.1
Simple Phase Failure Detection
At each system cycle the simple phase failure detection examines, whether the sum of the
phase voltage is within a threshold around zero. If the sum is greater than the threshold,
because one or two phase are cut off, a voltage phase failure is flagged with Bit 1 in the
Error-Byte
(see
NTG-3000 – Description of Protocol for Data Transmission
).
Disadvantage of this phase failure analysis method:
-
In three-phase systems the neutral wire has to be connected, otherwise the algorithm
does not work
-
The failure of three voltage phases is not recognized
13.2
Advanced Phase Failure Detection
The extended voltage phase failure detection compares at each system-cycle the values of the
individual phases together. In case of failure of one, two or three phases the comparison fails.
Via Bit 2 in the
Error-Byte
(
NTG-3000 – Transducer
) an error is displayed via
PROFIBUS
and Ethernet.
In this case the algorithm operates as shown on the picture below.
|U
1
|
|U
2
|
|U
3
|
PT1
25ms
LVM
QM
PT1
25ms
0,501124
LVM
QM
Σ
π
-8,8764e-3
PT1
25ms
LVM
QM
&
1,5
π
1,5
π
1,5
π
Note:
If the analog input filter is enabled (see 11), the advanced phase failure detection (see
12.2) is disabled!
