SEG Electronics GmbH
Manual MRG3
44
DOK-TD-MRG3, Rev. D
5.4.3 Threshold values of frequency supervision
The frequency supervision of MRG3 has three frequency elements that are independent from each
other. Dependening on whether the pick-up value was set above or below the nominal frequency,
these elements can be used for over- or for under frequency supervision.
Dependent on the preset nominal frequency f
N
the pickup values from 30 Hz up to 70 Hz at f
N
= 50
Hz and from 40 Hz to 80 Hz at f
N
= 60 Hz can be set.
During setting of the pickup values f1 - f3 the display shows the values in Hz. A value of for in-
stance 49,8 Hz is indicated with "4980".
The setting is accompanied by the following LEDs:
f1
f + 1 + <(>)
f2
f + 2 + >(<)
f3
f + 3 + >(<)
If the rated frequency is exceeded or if it falls short, the “>” sign changes to “<” and vice versa.
The function of the individual frequency elements can be deactivated by setting the pickup values
to "EXIT".
The setting value “EXIT“ corresponds to the rated frequency.
5.4.4 Tripping delays for the frequency elements
Tripping delays t
f1
t
f3
of the three frequency elements can be independently set from t
f1min
- 300 s.
The setting is accompanied by the following LEDs:
tf1
f + 1 + t>
tf2
f + 2 + t>
tf3
f + 3 + t>
The minimum tripping delay tf1min of the relay depends upon the number of set measuring repeti-
tions T (periods) and amounts to:
T
t
f,min
2....49
(T+1)•20 ms
50....69
(T -
49)•50 ms + 1 s
70....99
(T -
69)•100 ms + 2 s
When setting the tripping delay to "EXIT" by pressing push button <+> up to the maximum setting
value, the corresponding tripping relay is blocked. Pickup of the frequency element is however dis-
played on the front plate by the corresponding LED, an assigned alarm re-lay is also activated. This
setting applies to 50 Hz and 60 Hz.
5.4.5 Parameter setting for vector surge supervision or df/dt speed
By means of the parameter for the selection between vector surge function or df/dt supervision
(see chapter 5.3.7) it can be determined which of the two functions shall be enabled.
Parameter setting of vector surge supervision Both the vector surge angle
as well as the trip-
ping logic concerning the vector surge have to be adjusted for a vector surge supervision.
If the tripping logic is set to 1-OFF-3 ("1Ph" on the display), the relay trips as soon as the measured
vector surge angle has exceeded the set value
in one of the three phases. This is the more
sensitive adjustment when compared with the three phase tripping logic
3-of-3 (= "3Ph" on the display), where tripping occurs only if the vector surge angle exceeds the set
value in all three phases.
We recommend choosing the one phase tripping logic "1Ph". Only if this adjustment is too suscep-
tible to interferences, adjustment "3Ph" should be used.
