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AVR System

KTC AVR System is a fully reliable, microprocessor based system to maintain a stable voltage on the load side of the power transformers when the network load condition is fluctuating. The heart of the system is AVR KT30 relays. By measuring the outgoing voltage of power transformer with an AVR system, the On-Load Tap-Changer (OLTC) can be controlled which results in a stable output voltage.
AVR KT30 relay getting the related samples from output voltage of power transformers performs the related control on OLTC.

Some of the main features of KTC AVR System are as follow:

• Automatic controlling of transformers output voltage equipped with motor driven On-Load Tap-changer (OLTC).

• Displaying of Voltage, Tap position, Current and Power Factor on both Seven-segment and LCD.

• Line drop and Z compensation

• Voltage setting remotely controllable (3 load shedding inputs and 4-20 mA input signal)

• Time delay 1 definite inverse & Time delay 2 (can be switched off)

• Tap Blocking capability for each of U> , U< , I>

• Password protected against unauthorized people for changing the settings

Internal computation to minimize circulation current of transformers, in parallel connection (parallel card not required, only in KT30P series)

• Basic controls such as Auto/Manual, Individual/Master/parallel, manual Tap Raising, Manual Tap Lowering and … (only in KT30T series)

• Power supply: Self-power or 60-160 VDC/AC

• Output relays: Raise, Lower, over voltage, Under volt age and Over current

• Output signals: regulator blocking tap block, more circulating current, AVR faulty, out of steps, on other tap, tap changer failure, simultaneity time failure and serial communication error (in parallel mode)

• Data logging (V, I, Tap position, Power Factor) for several month and online printing (only in KT30L series)

Compliance with IEC60255-5 :

• 2000-12 , IEC 255-21: 1986-16 , EN55011 : 1998 +A1 : 1999

AVRs and optional features
Due to different technical requirements, KTC offers AVRs with different options and features. Consequently, the product is designated with different series as follow:
KT30P: Capability of automatic minimizing of circulating current when two transformers are controlled by two AVR in parallel mode.

KT30L: Logging and recording capabilities for voltage, current, Tap position, power factor etc. on internal memory for several mounts and online printing on external printer.
KT30T: AVR with Basic options such as Auto/Manual selector, Raise and Lower push button, Individual/Master/Parallel selector, 110 VDC signal lamp
Also AVRs with composition of above mentioned features are also available and are called as KT30PL, KT30PT, KT30LT, KT30PLT

Technical Spesifications:

 

Setting ranges
Voltage level:	85... 127V, Setting in steps of 0.5 V
Rated frequency:	45 ... 55 Hz
Bandwidth:	± 0.5% ... ± 9% of desired voltage
Delay time1:	0 ... 180 s, linear or inverse time response selectable
Delay time 2:	0 ... 10 s, between consecutive tap changing operations can be switched off.
TAP Changing permissible time:	0 ... 10 S
Simultaneity permissible time:	0 ... 10 S
Line drop compensator:	Simulation of line impedances,Setting of Ur= 0 ... + 25 V,Setting of Ux= 0 ...+ 25 V,
In steps of 1 V, applicable to all measuring transformer circuits Z-compensation:	Load-dependent, Setting of voltage  increase 0...15 % of
Desired voltage, Setting of limitation	0 ... 15 % of
Desired voltage
Parallel stability:	0... 25% desired value of the voltage level, in steps of 1%
Load shedding:	3 Inputs each 0 ... 9 % of desired voltage, Programmable in steps of 1%, 7 steps access able
Under voltage blocking:	80... 95% of desired voltage, setting in steps of 1%
Over voltage blocking:	105 ... 125 % of desired voltage, setting in steps of 1%
Over current blocking:	100...210 % of rated current of current transformer, setting in steps of 1%
K-factor (spreading):	t o be set according to the ratio of max. Operating current to rated current of C.T, setting range 0.5 ... 1.0 in steps of 0.01
Blocking code:	0... 7 in order to block relays command at out of range states.

 

Controls and indication elements
Function keys:	MODE - ENTER - UP - DOWN
Indication field:	2x2 LCD, 6 digit 7-segment LED display, 1 LED lamp each for indicating kV, V, %, S, U>, U<, I>, Remote, Tap changing time, simultaneity time, parallel, serial connection and for preliminary signals RAISE and LOWER
Output relays:	1 Relay each for RAISE and LOWER control pulses, with 1 N/O contact Signalling relay of under voltage blocking with 1 N/O contact Signalling relay of over voltage blocking, with 1 N/O contact Signalling relay of over current blocking with 1 N/O contact Make/break capability of all relay contacts 220 Vac 10 A / 110 Vdc 0.3 A
Output signals (isolated):	Simultaneity time failure, Reg blocking , permissible time failure,out of step, More circulating current, AVR faulty, No other tap, Serial connection error
Inputs:	Voltage transformer 85... 127 V measuring range 70 ... 127 V, r.m.s. Value, Sampling intervals 1.0s, error < 0.3 %, burden < 3 VA Current transformer 1/5 A, burden < 1 VA permissible overload of current path 2 x In permanent, 20 x In for 1 sec duration 3 Inputs with potential separation for load shedding 1 Input with potential separation for remote control 9 Input with potential separation for individual switch, parallel switch, Master switch, follower switch, auto/Manual switch, Remote switch, Lower contact, Raise contact, Simultaneity contact
Serial port :	Two RS232 port for connection to other KT30 and to acomputer or RTU. (RS232 can be replaced by RS485 for serial bus connection) Auxiliary supply : 60 .. 140V AC/DC (optional)
Burden:	10 VA
Options on AVR:	Parallel option for reduce circulation current in parallel transformers logger card for saving data (V, I , Tap, I , ...) in memory and connect to printer for online data printing Basic AVR panel include Auto/Man, Ind/Master/Parallel, Raise, Lower
Accessories :	CKT52 cable for AVRs with parallel option

 

AVR Panel
Depending on the quantity of AVR relays, AVR panels are given the names single AVR panel (KTAP-104) and double AVR panel (KTAP304). Main mechanical specification of the panels are as follows:
General design of panels are free-standing with internal 19 swing brocket with 180 degree rotating angle. The thickness of steel sheets is 2 mm acc. to DIN standards.
Main structure of panel is modular and front access with internal tray, for surface mounted components.
Internal trays are galvanized or painted as per customer request.
Profile design of elements are so, which the assembly of equipment, supports, busbars, poles etc. is facilitated.
Paint-able parts of panels, after derusting and degreasing is washed and phosphated and then painted applying electrostatic painting method. Normally the RAL7032 or RAL7035 are applied for painting but other requests are possible.
For the AVR panels degree of protection is generally IP4X.

Standard dimensions of LV cubicles is as following :
- Height 2200 mm
- Width 800 mm
- Depth 800 mm
Applied standards for manufacturing of panels are:
IEC 50, IEC 144, IEC 439, IEC 668, IEC 621, IEC 664, IEC 890, IEC 947, and also
VDE 0660