Novatek-electro OM-310, Руководство пользователя

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ОМ-310
NOVATEK-ELECTRO
When

=2, the thresholds values (kW) are defined as follows:
Main threshold (kW) = “Pnn” * “P1F” / “100”, where
“Pnn” – cumulative rated load wattage, kW;
“P1F” – main threshold, %.
Additional threshold (kW) = “Pnn” * “P2F” / “100”, where
“P2F” – additional threshold, %.
At any value of rPn, the additional load energizing threshold shall be determined as:
Energizing threshold (kW) = (“Pnn” * “P2n”) /(“100”), where
“P2F” – additional load energizing threshold, %.
1.2.6 Protection functions
1.2.6.1 Protection types
OM-310 device provides the following types of load protection:
- maximum phase current;
- against line-to-earth fault (based on zero sequence current):
- for minimum line voltage;
- for maximum line voltage;
- for line voltages imbalance (voltage negative sequence);
- for phase sequence order;
- starter unit operability control.
1.2.6.2 The overcurrent protection parameters are assigned relatively to the rated load current In (“

” parame-
ter).
1.2.6.3 Overcurrent protection
The overcurrent protection is of three-phase type. It is engaged when at least one of the phase current values
reach the tripping threshold.
The protection has a time delay setting. The delay can be independent (constant), or dependent ( SIT - reverse
dependent; VIT or LTI – very reverse dependent; EIT - extremely reverse dependent; UIT – ultra reverse depen-
dent; RI –type delay) - the tripping curves are displayed in Appendix 1.
When independent time delay protection is activated (fig. 1.4), the load relay is de-energized if one of the phas-
es current exceeds the threshold value within T period of time (parameter “



” ).
Is = “



” (tripping ratio) * In (load rated current), and T –
protection tripping delay time
Example. When



= 4.0, In = 10,



= 10.0, the load
relay shall open in 10 sec after one of the phase currents crosses
40 A value.
Figure 1.4 - Principle of protection with an independent time delay
The operation of the dependent time delay protection (Fig. 1.5) conforms to IEC 60255-3 and BS 142 stan-
dards.
In corresponds to “ind” setting (rated current of
load);
T (parameter “



” – protection function time
constant) – corresponds to the trip delay time for 10 In.
To deal with very high amperage currents the
protection has a feature with an independent time delay: