DMV-EP

 EuroProt familija
DIGITAL MOTOR PROTECTION
 
The digital motor protection of type DMV-EP is applied as a complex many-sided protection in a high level to protect three phase high voltage motors built in industrial plants and auxiliary supply system of a power plants. For optimum utilization of the motor capability, a protection has to be applied suitable to sense all the possible faults particularly overheating due to an overloading to avoid costly rewind and loss of producing time.

 
DMV-EP
 
Main features
 
  • Modern digital parametering (setting) method to get large setting ranges for each protection part.
  • Password protection against unauthorized setting action
  • Fast checking possibility of the protection setting data
  • Fast inquiring possibility of the actual "on line" operating data, the actual motor temperature rising value and the sum of protection working counters
  • 4 output contacts, programmable by software matrix
  • Real time clock handling synchronizable by external PC or by local area radio transmitter
  • RS 232 or optical fibre cable for external communication
  • Immediately appearing "messages" on occurring protection events
  • Event log storing 50 events and digital event sequence recorder recording 300 events with 1 ms resolution is built in the device. Deleting all events by hand may be made by external PC only
 
Main functions
 
  • Short circuit function to make fast trip when phase-to-phase or three phase fault occurs on motor stator winding, at motor terminals or on feeder cable till main current transformers
  • Earth fault function to trip when earth fault occurs on motor stator winding, at motor terminals or on feeder cable till main current transformers (or toroid type current transformer)
  • Overloading function 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 the motor 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 function 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 function 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 network level
  • Load loss function 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
  • Function 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 function protects the motor against severe damage on starting by relative fast trip


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

Setting (parametering) and checking of protection, inquiring of the working data, events and signals, setting of software matrix, and handling of automatic signals (messages) is possible with a built-in LCD of 2×16 characters and six push-buttons on interactive mode by the aid of a menu system or with an external PC. ELKO-PROTECTA gives a handling program together with the DMV-EP motor protection to make handling functions possible by an external PC.
 
Technical data
 
 
Rated secondary current, In
Rated zero sequence current, Ino
(other value can be given when ordering)
 1 A, or 5 A
0.1 A, 1 A, 5 A
Primary current of feeding C.T. 50 to 1500 A, step 25 A
Primary current ratio, zero sequence C.T. in case of toroidal type C.T. 150/5 A

Rated frequency

 50 Hz (60 Hz on request)
Overload capacity, in current circuits, continuous
1 s		 4×In
100×In (if In = 1 A)
50×In (if In = 5 A)
Dynamic current limit 100×In
Setting ranges:
Motor rated current, In
in per cent of the main C.T. rated current, In / I 		30 to 120 %, step 2 %
Idle operation minimum threshold current (fixed) IIDLE / In = 15 %
Phase fault O.C. relay starting current, I> / I
time delaying, t (I>)		 50 to 1500 %, step 10 %
0 to 60000 ms, step 10 ms
Earth fault O.C. relay starting current, 3Io> / I
time delaying, t(3Io>)		 10 to 100 %, step 2 %
0 to 60000 ms, step 10 ms
Motor rated temperature rising to its ambient when the motor load is In rated current Qn = 10 to 100 °C, step 1 °C
Overheating previous alarm signal setting value
in per cent to the motor rated temperature rising		 Qp / Qn = 60 to 160 %, step 2 %
Thermal overloading (overheating) trip setting value
in per cent to the motor rated temperature rising		 Qt / Qn = 80 to 180 %, step 2 %
Limit temperature rising to block the starting again command in per cent to the motor rated temperature rising Qb / Qn = 60 to 160 %, 2 %
Time constant for rotating motor temperature rising and cooling TR = 2 to 200 min., step 1 min.
Standing motor cooling time constant in per cent
to the time constant for rotating motor		 TC / TR (Tcool / Trise) =
100 to 400 %, step 100 %
Asymmetry protection starting value, fixed I2/In = 15 %
Asymmetry protection inverse definite minimum time relay, maximum time delaying at fixed starting current (I2 = 0.15×In) t as = 10 to 80 s, step 2 s
Asymmetry protection inverse definite minimum time relay, minimum time delaying at very high I2 current t asmin = 50 to 500 ms, step 50 ms
Load loss protection starting current in per cent to the motor rated current It < / In = 30 to 60 %, step 5 %
Load loss protection time delaying t(It) = 1 to 10 s, step 1 s
Starting period setting value tst = 5 to 100 s, step 5 s
Fault during starting period, setting current Ist / In = 200 to 800 %, 10 %
At heavy starting setting, during the starting period,
the heating current
 I2 / 2, fixed
Bearing or rotor stalling prot. after starting period 2xIn, if t > tst
Accuracy, current relays (over 50 % In) ± 2 %
Accuracy, timers ± 3 ms, at step of 10 ms
± 12 ms, at step of 1 s
Current relays, resetting ratio 95%, fixed
External communication RS 232 or optical fibre cable
External communication (BaudRate) 150 to 19200 Baud, step 2 times
Automatic daily self check, starting time 0 to 23 hour 59 minute, step 1 minute
Automatic daily self check, blocking setting to 60 minute
No. of substation in a system 0 to 253
No. of device in a substation 0 to 253
Number of output relays 8 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, 110 V
88 to 310 V
48 V
DC consumption, basic state
at working		 < 7 W
< 9 W
Permissive ambient temperature 0 °C to 50 °C
Insulation test (IEC 255) 2 kV, 50 Hz
5 kV, 1.2/50 ms
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, cases
 
The device is a member of the device family EuroProt. It has two different designs. The one is a device for rack mounting to a 19" standard cabinet frame, the other is a flash mounting device or mounting raising to a panel. Its size depends, of course, on the design chosen.

Design
Width
Height
Depth
Rack mounting
483 mm
132,5 mm
201 mm
Panel mounting
384 mm
250 mm
250 mm
 
Options
 
  • Disturbance recorder
  • Interface to a SCADA system
  • Output contacts with 4 A DC breaking capability
  • Opto-coupled digital inputs (in the modularity of 8 pcs)
Information required with order
 
  • Type of protection [DMV-EP]
  • Rated C.T. current [1 A, 5 A]
  • Feeding type of zero sequence relays [main C.T., toroidal type C.T.]
  • In case of toroidal type C.T., its ratio [150 / 5 A or others]
  • Auxiliary DC voltage [220 V, 110 V, or other]