DMV-WP

 OmegaProt familija
DIGITAL MOTOR PROTECTION
 
The type DMV-WP device belongs to the WProt device family. Features of this device family are nearby so varied as the other up-to-date devices made by ELKO-PROTECTA but these are extremely small-sized and their mounting is very simple. The devices are stackable to a standard W-rail, which is generally used by the electrical power industry. The small-sized design is produced by a healthy relational compromise so that wide ranging application is not limited.
 
DMV-OP
 
Main features of WProt family
 
  • Small-sized device based on microprocessor and stackable to a standard W-rail
  • It is smaller than other devices of similar features
  • Three analogue inputs (for receiving currents, voltages)
  • Four independent output relay contacts which can be freely programmed by a software matrix and each has possibility to be set for sealing-in
  • Two optical fibre connectors (transmitter, receiver) for communicating with a SCADA system or with a PC, and for programming the protection, receiving on-line informations, and reading events stored
  • Eight signal LED on the front plate of protection for getting additional informations about the operation
  • Acknowledge pushbutton for acknowledgement of signals and for solving relays being sealed-in
  • Terminals are on the front plate of case
 
Application field
 
The digital motor protection of type DMV-WP is mainly applied as a complex many sided protection in a high level to three phase high voltage motors built in industial plants and auxiliary supply system of a power plants.

The main tasks of motor protection:

  • Short circuit protection to make fast trip when phase-to-phase or three phase fault occures on motor stator winding, at motor terminals or on feeder cable till main current transformers
  • Earth fault protection to trip when phase-to-ground fault occures on motor stator winding, at motor terminals or on feeder cable till main current transformers (or toroid type current transformer)
  • Overloading protection works as a temperature replica device i.e. it determines the motor overheating by taking motor current and motor thermal characteristic data into account, and gives first alarm only, afterwards trips the motor on dangerous overheating. The protection calculates the motor overheating Q(t) and cooling Qh(t) according to the equations as follows:

    Q(t) = Q0 + ( Qn (Ik / Inm)2 - Q0)(1 - e-t/Tm), i Qh(t) = Q0e-t/Th

    where:
    Inm - "motor rated current"
    Qn - temperature rising at "motor rated current" Inm
    Q(t) - inner temperature rising of motor after t time period
    Q0 - previous overheating of motor
    Tm - warming and cooling time constant of motor on rotating condition
    Th - cooling time constant of motor on standing condition

  • Blocking-on-starting-again an overheated motor protection prevents a motor to take again into operation if it is in an overheating condition due to a former overheating or any other reason until the motor cools under a presetting temperature
  • Asymmetry protection protects a motor against abnormal overheating of stator and rotor due to a phase loss, two phase operation, or asymmetry caused by a breakdown on a higher voltage level network
  • Load loss protection which is necessary at some drives (e.g. a motor drives a pump) and trips the motor if a sudden load loss is dangerous due to a technological reason
  • Protection of a motor with heavy starting condition makes possible that the preset overheating value of a motor of long running up time and starting with heavy load be higher then that on normal operation since it is a cool starting condition, and in spite of that safe overheating protection be available on normal operation
  • Rotor or bearing stalling protection protects the motor against severe damage on starting by relative fast trip

Each protection functions listed above may be separately blocked and made active.

Setting (parametring) and checking of protection, writting of the working data, events and signals, setting of software matrix, and handling of automatic signals (messages) is possible with external PC or other external computer. A handling program is delivered together with the DMV-WP motor protection to make handling functions possible. The device can be handled on interactive mode by the aid of a menu system.
 
Technical data
 
Rated secondary current, In
Rated zero sequence current, Ino		 1 A or 5 A
0,1 A, 1 A or 5 A
Main C.T. primaty current 50-1500 A, step 25 A
Zero sequence main C.T. primary rated current
ratio in case of a toroidal C.T.		 50-1500 A, step 25 A
150/5 A
Rated frequency 50 Hz
Overload capacity , continuous
1s		 2xIn
100xIn (In=1 A), 50xIn (In=5 A)
Dynamic current limit 100xIn
Setting ranges
Motor rated current, Inm
in per cent of the main C.T. rated current, Inm / In		 30-120%, step 2%
Idle operation minimum threshold current (fixed) IIDLE/Inm=15%
Phase fault O.C. relay starting current, I> / In
time delaying, t (I>)		 50-1500%, step 10%
0-60000 ms, step 10 ms
Phase fault O.C. relay during starting period, I> Iiz/Inm 200-1200%, step 10%
Earth fault protection, 3I0>/IAV0
time delaying, t(3I0>)		 10-100%, step 2%
0-60000 ms, step 10 ms
Motor rated temperature rising to the ambient temperature at load Inm Qn=10-100ºC, step 1ºC
Temperature of overheating (overloading) pre-signal Qe/Qn=60-160%, step 2%
Temperature of overheating (overloading) tripping Qk/Qn=80-180%, step 2%
Temperature of blocking-on-starting-again an overheated motor Qt/Qn=60-160%, step 2%
Warming and cooling time constant of motor on rotating condition Tm=2-200 min, step 1 min
Cooling time constant of motor on standing condition Th/Tm=100-400%, step 100%
Asymmetry protection starting value, fixed I2/In=15%
Asymmetry protection, time delaying at I2 = 0.15xIn
lower limit of time delaying		 tas=10-80 s, step 2 s
tas min=50-500 ms, step 50
Load loss protection, undercurrent relay It>/Inm=30-60%, step 5%
Load loss protection time delaying t(It)=1-10 s, step 1 s
Motor starting time value tst=5-100 s, step 5 s
Warming current at heavy starting setting, during the starting period I2/2, fixed
Bearing or rotor stalling prot. after starting period 2xInm, for t>tst
Accuracy, current relays
Accuracy, timers		 ± 2%
± 3 ms, step 10 ms
± 12 ms, step 1 ms
Current relays, resetting ratio 95%
External communication fibre optical cable
External communication speed (BaudRate) 150 to 19200, step:2x
Automatic daily self check, starting time 0 to 23 h 59 min, step: 1 min
Automatic self check, blocking setting to 60 min
Number of output relays 4 pcs
Output contacts ratings,
rated switching voltage
continuous load current
switching on current
breaking current at 220 V DC,
pure conductive circuit
L/R = 40 ms load
250 V
8 A
16 A

0,25 A
0,14 A
Auxiliary DC voltage (the same supply unit)
voltage tolerance
optionally, on ordering		 220 V or 110 V
88 V to 310 V
48 V
DC consumption, basic state
at working		 <7 W
<9 W
Permissive ambient temperature 0º to 50º C
Insulation test (IEC 255) 2 kV, 50 Hz
5 kV, 1.2/50 μs
Disturbance test (IEC 255) 2,5 kV, 1 MHz
Electrostatic discharge test (ESD; IEC 801-2) 8 kV
Burst test, (IEC 801-4) 2 kV
 
Design, size
 
The DMV-WP motor protection is built into the closed dustproof steel case, controlled by microprocessors, set up with IC's, placed to PCB's. The case may be stackable to a standard W-rail, width in the rail is 120 mm. 16 terminals are placed on the front plate of case, through them external connection may be made. The optical fibre cable connections are put to the upper part of the front plate at left.

Width
Height
Depth
120 mm
90 mm
90 mm
 
Data to be ordered
 
  • Type of protection [DMV-WP]
  • Rated C.T. current [1 A, 5 A]
  • Whether is the d.c. (logical) busbar differential protection contact an NC or NO type?
  • Feeding of zero sequence relais [main C.T., toroidal type C.T.]
  • In case of toroidal type C.T. its ratio [150/5A or others]
  • If an output contact is needed for alarm of the monitoring system an NC contact of K4 should be ordered.