Seg WIC1 User Manual

4.8 ThR – Thermal Overload [49]
The thermal overload protection »ThR« protects the connected object against overload.
The amount of overload is determined based on the measured RMS phase currents. The
thermal overload module »ThR« provides two di󰊞erent overload warning levels:
• The Pre-Alarm level is settable via »Pre-Alarm Lev.« between 50% and 100% and•
issues a Pre-Alarm signal if the set value is exceeded.
• The Trip level is 󰊟xed at 100%. If this level is reached a Pickup signal and either a•
Trip (Operate) or an Alarm signal are issued.
The WIC1 calculates the thermal load of the equipment by using the existing measured
values and the parameter settings. When knowing the thermal constants, the temperature
of the equipment can be established (simulated).
The thermal level is reset to zero in any of the following cases:
• a change of the con󰊟guration (i. e. changed settings / parameters);•
• as soon as the thermal overload module is deactivated (signal »ThR .•
Active« = “False”).
•
manually, via the Direct Control [Operation / Reset] »Reset Thermal Level«.
•
Tripping Time
The general tripping times of the overload protection can be gathered from the
following equation:
t = τ-warm ⋅ ln
⎛
⎝
I
2
- Ip
2
I
2
-
(
K ⋅ Ib
)
2
⎞
⎠
Legend:
• t = tripping delay•
• τ-warm = warming-up time constant•
• τ-cool = cooling time constant•
• Ib = base current: maximum permissible thermal continuous current•
•
K = overload factor: The maximum thermal limit is de󰊟ned as K⋅Ib, the product of
•
the overload factor and the base current.
• I = measured current (in units of In)•
• Ip = preload current•
160 WIC1 WIC1-1.0-EN-MAN
4 Protective Elements
4.8 ThR – Thermal Overload [49]

Seg WIC1 Specifications

General

Brand	Seg
Model	WIC1
Category	Relays
Language	English