Inverse Time (59Nit) - Siemens 7SR21 Manual

Vs
Phase
(Volts)
E
Check correct indication, trip output, alarm contacts, waveform record.

2.13.7 Inverse Time (59NIT)

It will be advantageous to map the function being tested to temporarily drive the relevant Pickup output in the
Pickup Config sub-menu in the Output Config menu as this will allow the Pick-up led to operate for the function.
Gradually increase voltage until Pickup LED operates.
Apply 2x setting voltage and record operating time,
Apply a higher multiple of setting voltage and record operating time.
Compare to calculated values for operating times from:
Where M = Time multiplier and Vn/Vs = multiple of setting.
P.U.
D.O. Ph.
&
TIMING
E
TESTS
2.13.7.1 Element Blocking
The Neutral Overvoltage elements can be blocked by Binary Input Inhibit. This functionality should be checked.
Check correct indication, trip output, alarm contacts, waveform record.
When testing is complete reinstate any of the disabled functions.
©2010 Siemens Protection Devices Limited
DTL P.U. Current
(sec) Volts
(
t sec onds
op
Operate Voltage
Vs
TM
P.U.
(V)
(Volts)
Element
59NIT
59NDT
7SR21 & 7SR22 Argus Commissioning and Maintenance
Operat
e Time
2x Vs
⎡ ⎤
) 1
=
⎢ ⎥
) M [ ]
−
Vn
⎣ 1 ⎦
Vs
D.O.
Tol
(Volts)
Tolerence
Operate Time
2 x Vs x Vs
(sec) (sec)
BI Inhibits
Chapter 6 Page 54 of 69
Tol