MESSKO MTeC EPT202, Руководство по эксплуатации

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13
BA 2076/02/01
5 5
5 5
5 Function Description Function Description
Function Description Function Description
Function Description
5.1 5.1 5.1 5.1 5.1 Basic Function Basic Function Basic Function Basic Function Basic Function
The EPT202 is used to measure the temperature of
transformers or similar devices. The oil temperature is fed in to
the EPT202 via a temperature sensor. Internally the EPT202
calculates the thermal image (Hotspot temperature) in acc.
with IEC 354 or ANSI standard and indicates the oil and
winding temperature on its display.
The winding temperature (Hotspot) is calculated acc. to the
following equations:
Calculation acc. to IEC 354:
Calculation acc. to ANSI IEEE Std. C57.91:1995
Whereby: : Hotspot temperature
: Top-Oil temperature
: Hotspot factor
: Gradient of the average winding
temperature over average oil
temperature at rated current
: Gradient of the Hotspot temperature
over the Top-Oil temperature at rated
load
: Load factor (actual current / rated
current)
: Winding exponent
: Exponent for the calculation of the
actual Hotspot temperature
: Time constant of oil
If the calculation is to be done according to ANSI standards, a
Hotspot factor of 1,0 must be used and instead of the winding
exponent the appropriate ASNI exponent (2m) must be put in
to the equation.
5.4 5.4
5.4 5.4 5.4
Device Self-Monitoring Device Self-Monitoring
Device Self-Monitoring Device Self-Monitoring Device Self-Monitoring
The EPT202 continuously monitors itself. The following errors
are detected by the device.
•
Defective sensor
•
Analog output 1 (oil temperature) open
•
Analog output 2 (winding temperature) open
•
Error of the supply voltage
When one of these errors has been detected, the ERROR
contact is closed, the ERROR LED goes on, the error is
indicated on the display and in the visualization software, and
the analog outputs (if current output) indicate the error signal.
CAUTION CAUTION CAUTION CAUTION CAUTION
When the device detects the error „sensor defective“ or an
error of the supply voltage, the switching contacts S1 to
S4 are closed and the ALARM and TRIP contacts retain
their current status.
5.5 5.5
5.5 5.5 5.5
Switching Contacts S1 to S4 Switching Contacts S1 to S4
Switching Contacts S1 to S4 Switching Contacts S1 to S4 Switching Contacts S1 to S4
The EPT202 is equipped with 4 relay contacts to activate fans
or pumps. These contacts can be turned on and off via the oil
or the winding temperature or, as an alternative, can be
turned permanently on by hand. The hysteresis and the delay
time of the contacts can be parameterized as desired.
The switching contacts S1 to S4 also switch the cooling-
phase-specific winding parameters.
5.6 5.6 5.6 5.6 5.6 Cooling-Phase-Specific Parameter Records Cooling-Phase-Specific Parameter Records Cooling-Phase-Specific Parameter Records Cooling-Phase-Specific Parameter Records Cooling-Phase-Specific Parameter Records
The winding parameters for 5 different cooling stages can be
stored on the EPT202 with the following values.
• Rated CT current
•
Gradient gr
•
Winding exponent y
•
Winding time constant
t
5 Function Description
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
− × × × + =
−
τ
t
y
r Oil Top Spot Hot
e K g H θ (t) θ
1
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
− × × + =
−
τ
t
m
H,R Oil Top Spot Hot
e K ∆θ θ (t) θ
1
2
TopOil
θ
H
(t) θ
Spot Hot
r
g
R H
θ
,
∆
K
y
m
τ
5.2 5.2
5.2 5.2 5.2
Sensor Inputs Sensor Inputs
Sensor Inputs Sensor Inputs Sensor Inputs
A Pt100 sensor or a sensor with an active or passive
4 to 20 mA output signal can be used as an input sensor. The
sensor type (Pt100 or 4 to 20 mA) must be parameterized by
the user.
Through the use of an optional 4 to 20mA sensor, the EPT202
can record and store the ambient temperature by means of a
data logging function. The Top-Oil temperature must then be
detected by a Pt100 sensor.
The temperature range of the oil temperature sensor input is
set to -20 to +140 °C (standard). Other temperature ranges are
also available on request. The temperature range is also used
to indicate the event of a defect sensor, which happens when
the temperature exceeds or drops below the admissible range.
When a sensor with 4 to 20 mA output signal is used, the
measuring range of the sensor output must comply to the
temperature range of the EPT202. Please check the nameplate
information.
5.3 Analog Outputs 5.3 Analog Outputs
5.3 Analog Outputs 5.3 Analog Outputs
5.3 Analog Outputs
The basic device is equipped with one analog output each for
transmission of the oil temperature and the winding
temperature. The output signal can be parameterized. The
following output signals can be set as standard.
•
0 to 20 mA (error signal > 22 mA)
•
4 to 20 mA (error signal > 22 mA)
•
4 to 20 mA (error signal < 3.6 mA)
•
0 to 1 mA
•
0 to 10 V
Additional output signals can be implemented with a signal
converter. The error signal is output when a defective sensor
or an open analog output is detected.