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2. 2. 2. 2.
2.1. PROTECTION FUNCTIONS
The MOV general connections diagram, and the external voltage
following diagram:
B1
521
520
B2
where:V1 = Undervoltage on bus 1.
V2 = Undervoltage on bus 2 (or line 2)
V3 = Undervoltage on line phase A.
V4 = Undervoltage on line phase B.
V5 = Undervoltage on line phase C.
89 = Line Selector switch closed.
89 = Line Selector switch open.
* = logic AND.
+ = logic OR.
TMP = time setting for function A.
This function consists on detecting undervoltage (1.1. setting) on both sides of the side breaker (in case of
breaker and a half schemes), during a certain period of time (setting 2.1.). It monitors the Busbar voltage (V1) and
the line voltage values (V3, V4, V5) or V2, depending on the status of the line disconnection switch. The operation
of this function allows the side breaker to trip and signal undervoltage to the control system.
This function detects undervoltage (setting 1.1.) on the line side associated to the central breaker. In order
to monitor undervoltage on both sides of the central breaker, this function needs to be ANDed with function A' of
the MOV relay protecting the other two breakers (contacts in series).
GEK-106271
L1
89-1
89-2
L2
= V1 * ( V2 * 89 + (V3 * V4 * V5) * 89 ) * TMP
= ( V1 * 89 + (V3 * V4 * V5) * 89 ) * TMP'
MIV Digital Multifunctional Protective Relay
OPERATION PRINCIPLES
OPERATION PRINCIPLES
OPERATION PRINCIPLES
OPERATION PRINCIPLES
commuting
Va, Vb,
Vb
V3, V4,
V1
89-1
MO
V2
V2
MO
89-2
V1
V3, V4,
Vb
Va, Vb,
2. OPERATION PRINCIPLES
required is shown on the
89-1
89-2
2.1.1. A FUNCTION
2.1.2. FUNCTION - A'
7
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