Main Features; How To Choose The Current Transformer (C.T.) - Comar Condensatori MPR8 Serie Manual De Instrucciones

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Digital display
Display select
Program select
Reset

1. MAIN FEATURES

is an automatic microprocessor regulator which constantly controls the phase displacement
MPR
between current and voltages waves on zero crossover, and operates the switching on and off of
the capacitors steps which are necessary to reach and to maintain the required power factor. The
MPR is fitted with an input filter which allows correct operation and display even in presence of harmonics. The
central microprocessor unit controls all settings and parameters.

2. HOW to CHOOSE the CURRENT TRANSFORMER (C.T.)

Use a Current Transformer (C.T.) with 5A at secondary circuit and primary equal or slightly higher than the maximum
absorbed by the loads. The C.T. must be chosen in such a way to obtain a good current signal in the secondary circuit.
Current values between 0.5 and 5Amps are suitable to obtain good working conditions of the regulator.
The C.T. must be good quality (first class) and with power equal or higher to 5VA. If the C.T. has been mounted far
from the equipment, it needs to add the normal demanded the power consumed from the cables of connection
(normally 0.2VA per meter of bifilar lines with 2.5mm
connected in the circuit.
The equations, used to calculate the real losses, are the sequent:
ρ ρ ρ ρ
R=2x
xL/S
(Ω)
2
P=(R+0.08) x I
(VA)
ρ ρ ρ ρ
'
' is the electrical resistivity ( 0.018 for the copper )
'L' is the length of amperometric circuit (m)
'I' is Imax. at the secondary of C.T.
When single-phase inductive loads are connected (unbalanced three-phase system), place C.T. on the phase where
Power Factor is lower and/or where higher current value is absorbed.
The cables at the secondary of C.T. have to be of 2,5mm
The C.T. connection must not to be protected with fuses or interrupted by switch.
The C.T. has to be connected to the line, upstream the load and the P.F. Regulator: the C.T., can then measure the
current demanded by the load, inductive and capacitive. Possible capacitors for fixed P.F.Regulation will be mounted
downstream of the C.T., as they aren't used and dimensioned for the P.F. Regulation of transformers that feed the
load. It's important to check that the phase, where the C.T. is connected, is the same that will be connected to
terminals of the main switch, inside the equipment, signed with the letter "R" (L1).
Before doing any work on the C.T. circuit, be sure that the C.T. is short-circuited, otherwise dangerous voltages can
rise, add bring to breakdown the C.T.
P.F. correcting two or more lines (transformers in parallel), you need to use two or more C.T (.../5) of which the
secondary circuits will be supplied a add transformer with 5Amps at secondary: connect the current transformers at the
same phase. If two or more C.T. 's are used with an additional transformer, the value of the primary current is the sum
of each C.T. Example: n° 3 C.T. 's 500/5 = n° 1 C.T. 1500/5.
Connecting two or more cables (for load and P.F.Regulator) on the same terminal - phase "R"(L1) - from the general
main switch, It needs to pass through the hole of the C.T. all the derived cables.
Note. MPR regulators are able to detect automatically the current phasing of the CT. It is not necessary to ensure correct
polarity connections as with other Power Factor Regulators.
Power Factor Regulator
Φ Φ Φ Φ V
cos
A
° C
1 2 3 4 5 6
Select
C/K
PF
Prog.
made in Italy
2
section) and the power dissipated by others possible tools
Total resistance of amperometric circuit
Losses of amperometrical circuit
'S' is the across section of cables at the secondary of TA
'0.08' are the internal resistance of P.F. regulator
2
section.
10
Temperature
7 8
IND/CAP Led's
AUTO / MAN
_
+
C/K and PF
MPR8
sensor
Led's bank
selector
setting

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