Single Phase Voltage Regulator RAV-2
with control CTR-2
Instruction Manual MI-010
Page: 5/27
Rev. 06/2017
OBSERVATION 1: Input for connection of an independent external Voltage Transformer is
optional and has to be requested specifically on purchase order
OBSERVATION 2: Independent external Voltage Transformer is optional and also needs to be
requested specifically on purchase order
Star ("Y")
Features:
– Connections as per Figure 8;
– Regulator´s nominal voltage is
the nominal voltage between
phase and neutral of supply;
– For a purely resistive load phase
shift between current and
voltage measured in the
regulator would be 0º for all
regulators;
– Effective regulation: ±10% of
voltage between phase and
neutral in direct power flow;
EARTH CONNECTION OF A BANK OF REGULTORS
Proper grounding for a bank of single-phase voltage regulators must ensure resistance according to ABNT NBR
14039 which refers to medium voltage electrical installation between 1.0 kV to 36.2 kV.
ATENTON: If voltage difference between regulator´s tank and earth is bigger than 50V, it is
recommended to remove from service the complete bank of regulators from network and
amend grounding accordingly.
CASCADED VOLTAGE REGULATORS
We define cascaded voltage regulators when two or more bank of regulators are installed in a same network. This
condition can cause problems in the interactive operation between banks which need to be thoroughly studied so as
to determine optimal configuration and installation location. Otherwise, it may cause large fluctuations of voltage in
the network.
For a correct analysis of cascaded voltage regulation it is necessary to consider that changes in the tap changers of
each regulator are perceived both downstream, by voltage variation, and upstream by current variation.
For delta connections there is an additional complexity factor as differences are caused between the phases at the
point of location of each bank and its effect depends on the position of the tap changer, of load currents and
impedance of the network till that point.
Fault Effect
In a distribution network where there are N cascaded voltage regulators a critical state can be achieved in which all
regulators of all banks are boosting (giving the highest elevation), eg. 15% in delta connection. If there is a power
failure when energy returns and only for a moment load would be disconnected but as tap changer position will keep
as in full load. As losses would be smaller, tensions of up to 1,15N times of source nominal voltage can be present
at the last load bank.
A distribution network in which they are installed, cascade, N bank regulators, can stay in critical condition in which
all regulators of all banks are promoting the highest elevation, ie over 15% in delta connection. If in this condition,
any power failure at the time of return and for a moment, he drew the charge, but the positions of the switches still
remain as it were at full load. As the losses would be less, may occur voltages up to 1.15 N times the voltage of the
source in the last load bank
Effect of operations avalanche
When analyzing the performance of the 2 banks of regulators, RT1 and RT2, connected in series, according to the
scheme of Figure 9, we note that the bank downstreams, RT2, perceived a tap change taps at the rearmost bench,
RT1, due to the variation of tension that it causes. Also, tap changes of RT2, is perceived by RT1 due to changes in
ITB - Equipamentos Elétricos Ltda.
Figure 8: Star connection of three singe phase regulators in three phase line with neutral
consistently grounded.
S
S
o
u
r
c
e
SL
L
Neutral
L
o
a
d
Phase A
S
S
o
u
r
c
e
SL
L
Neutral
L
o
a
d
Fase A
L
L
o
a
d
Phase A
S
S
o
u
r
c
e
SL
Neutral
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