WO1989009507A1

WO1989009507A1 - Protective device for electrical motors and networks and temperature stabilizer

Info

Publication number: WO1989009507A1
Application number: PCT/EP1988/000248
Authority: WO
Inventors: Zoltan Graf Von Spanyol
Original assignee: Zoltan Graf Von Spanyol
Priority date: 1988-03-28
Filing date: 1988-03-28
Publication date: 1989-10-05
Also published as: EP0401213A1

Abstract

For electrical motors and networks, unlike for other currently used appliances, which are protected against excess current and short circuits, a protective device is absolutely essential, as well as a temperature stabilizer, because such a device, which does not indicate the overcurrent and the electrical fire that could result from it, but prevents such hazards, makes the electrical motors and networks perfectly safe to operate. Moreover, said protective device can be used in all circumstances and fitted even where the efficiency of traditional appliances is questionable or even non-existent. This is achieved because the device is based on the principle of parallel connection with the operating circuit and perceives the voltage components of the operating current. It can therefore also be used as a temperature stabilizer.

Description

Protection system for electric motors and networks as well as temperature stabilizer.

The invention relates to protection against overload, against electric fire according to the preamble of claim 1 and a temperature stabilizer according to the preamble of claim 2. The 4 (four) components characteristic of the circuit (such as voltage, current, temperature, resistance) are interconnected in a functional context. This means that the invention switches off the consumer in the event of a voltage drop. Schematic:

Voltage drop = overcurrent → heat development → increase in resistance.

The conductor is dimensioned on

- The size of the resilience through the formula

or in the case of 3 phases

through the formula

- the voltage drop through the formula

where q = line cross section / mm l = line length x = conductance e = voltage drop. The permitted voltage drop ε% is at nominal mains voltage

which is generally 5% of it

The circuit arrangement on the one hand - according to the preamble of claim 1 - a 100%

- Protection against overheating, against overload depending on the cross section of the conductor

- Protection against asymmetrical loads

- Protection against reverse induced voltage

- Protection against frequency changes

- protection against short circuit

- Protection against electric fire

- Protection with an explosion hazard

- Protection for heat operation (exceptionally warm or cold)

- Protection for periodic operation

- Protection for constant operation

- Ensure protection for the braked rotor, on the other hand

it should - according to the preamble of claim 2 - as a temperature stabilizer with the best sensitivity, operational safety and with optimal service life.

It is known to arrange the following apparatus to meet these requirements:

Bimetal

Strong current self-switch

Protection against melting. The working current flows through them, so they have to endure the on and off current surge as well as the transition effect. This means that their commissioning may have to be determined up to 4 - 6 times the nominal current. Furthermore, the effective current value in the event of a short circuit I _z = 30 kA _eff .

The effect of the arc is determined with the Joule integral as follows

This thermal energy is generated in the circuit during the final period (t _z ) with one (1) ohmic resistor.

In the links, the resistance on the contact elements occurs to the same extent

and so it is expected that

I _z ² = RI _e ² .

There is currently no protection against volume and film resistance (corrosion), although in most cases these two cause the fire

R _a + R _af + R _cu + R _v = R should be written down as series resistance, where

R _a = volume resistance; R _af = film resistance

R _cu = copper (as line) resistance R _v = consumer resistance; R = resulting resistance

In practice, these resistance values can change indefinitely. That is why I assume the internationally accepted operating temperature of the cables (conductors, Schinenj. As a function thereof, the maximum temperature of insulated cables is 45 ºC, that of bare cables and rails is max. 65 ºC, even if the ambient temperature during continuous operation 35 ºG is:

To do this, the resistance is calculated from the formula

of all places.

This formula also explains how the invention as a temperature stabilizer with the best sensitivity, operational reliability and the most optimal

Function duration is usable.

In the case of Cu

= Ambient temperature

= Heat temperature

and ΔR = R ₁ + R ₂ , since it is a series connection. The amount of current (I) can be determined from the formula of the drive power:

P = UIcos ℓ; (P = UI-cos ℓ. √3)

In the case of a network with constant voltage, two components of the line increase increase: the current strength and resistance. This increase can be such that it reaches the final value (I _z ). Invention No .: 14996: is a device for the case of acute danger of touch (p.3, line 26). This device only works as a result of a short circuit (S.3, Z.31) and phase earth fault (S.3, Z.7,76), it gives the presence of one or both signals, for which an extra circuit with its own power source (S.3 , Z.57,68) is applied.

Invention No .: 359585: is a protective device against overvoltages. It contains a relay with higher sensitivity and, if necessary, a series resistor or a calibration resistor, which are connected in series with the relay. The entire device is connected in parallel to the power grid. It is basically suitable and intended for DC voltage. However, use with AC voltage is possible if the device also has a rectifier in front of the relay (p.2, line 28).

In the above I have proven that the current security systems do not provide the necessary protection. This applies to the fuse as well as the bimetal and high-voltage small self-switch. The arc, including the transition effect, makes your operational reliability unreliable.

The thermistor: the main disadvantage that it can only be installed in a newly rewound motor. Even in a transformer only before impregnation. It is irreparable, unmistakable. Its operating temperature is only 175 ºC in the case of continuous operation. It must not be used when the rotor is braked or when there is a risk of explosion. In addition, it is only recommended in special cases.

The disadvantages of invention no .: 14996:

With star connection in the case of strong power, the star point must be grounded. According to the symbol (p.2) the breakdown protection (8) is installed between the star point and the protective earth. So the star point is not grounded.

It only sets in as a result of a short circuit and phase earth fault

Business. Since the arc burns the puncture protection (S.3, Z.31,

32, 33). So the short-circuit current flows through the protection system. Therefore, it is unsuitable in operating situations where there is a risk of fire and explosion. (The effective value of the short-circuit current: 30 kA = 30000 A).

- With delta connection (Δ) it is completely unusable.

- If one phase fails, it does not switch off; with star connection (Y), the device to be protected remains in operation due to induced voltage (U _i = 4.44.ε. Փ ≈ 195 V).

- There is no protection against volume resistance and heating.

- Since a separate power source is required for signaling, its condition affects operational safety.

- Because of the above-mentioned, it is also obvious that the invention no .: 14996 does not guarantee the safety of touch.

- It does not offer preventive protection, but signals the operational damage.

The disadvantages of invention no .: 359585:

The invention is on the primary side of the synchronous machine (at

Excitation coil of the rotor) can still be used against overvoltage.

- It does not work with a short circuit. (There is no overvoltage either).

- It offers no protection in the case of asymmetrical loads.

- It does not protect against warming, increase in resistance.

- The relay at normal voltage (below the response voltage) is in suspension (p.2, line 22). This condition is detrimental to operations.

- In the case of AC voltage, a rectifier must be connected in front of the relay coil.

The bimetal as a temperature stabilizer works mechanically, so it is unreliable.

The invention has for its object the necessary 100% protection

- in rooms and apparatus with a risk of explosion

- against overload

- against overheating

- against electric fire - against short circuit

- against frequency change

- against asymmetrical loading also in the following cases:

- heat operation (exceptionally warm or cold)

- periodic operation

- constant operation

- to grant the braked rotor to the industrial plants and all the devices with circuit, to increase the economy in every respect.

The object of the invention is to optimally operate apparatus, devices and operating rooms with a specific temperature requirement by means of an electronic temperature stabilizer.

This object is achieved in a generic device by the characterizing features of claims 1 and 2. Accordingly, it can also be seen that the invention does not require a temperature sensor.

The invention guarantees symmetrical loading, because if the impedances of the consumers in the symmetrical (120) phase shift are not equivalent, they shift the current in relation to the voltage with an angle, and this causes an asymmetrical loading. The asymmetrical load creates reactive current or reactive power.

P _m = reactive power

I _m = reactive current

I _f = phase current

U _f = phase voltage The reactive effect of the reactive current warms up the conductor, so the resistance of the conductor also increases. This means that the conductor with reactive current is much warmer than that with active current. As a result, the invention switches off the consumer. The unit of reactive power is:

P _m = U _f · I _f · sin ℓ / VAr = volt-amp reactive (kVAr).

Asymmetric loading also occurs when a phase conductor breaks.

The invention protects against frequency changes as follows: The choke has a self-induction. The induction coil produces the induction voltage. According to Lenz's law, this reverse voltage flows against the mains voltage. So we can call it an inductive voltage drop.

In the sinusoidal circuit:

i = i _m · sin ω. tu = u _m · sin (ωt + 90 º) sin (α + 90º) = cos α,

so u = u _{m · cos ω} · t

u _m = i _{m ·} 2 π · f · L = i _m · ω L /: √2 u = I .ω.L → X _L = ωL →

→ U = I .X _L The frequency change will change the (X _L ) resistance of the choke:

ω = 2πf X _L

Hz 1 / s Vs / A (H) Ω

50 314 0, 0955 30

100 628 0.0955 60

500 3140 0, 0955 300

If U = 220 VI = 0.5 A f = 50 Hz, then

The rotational frequency: ω = 2π f = 2 π 50 = 314 1 / s

The inductance:

ω = 2π f

Hz 1 / s Vs / A (H) Ω

50 314 1, 4 440

100 628 1, 4 880

500 3140 1, 4 4400

1000 6280 1, 4 8800

The advantages achieved with the invention are that

- it offers 100% protection against any disruptive factors and under all operating circumstances.

- It ensures the desired operating temperatures not mechanically, but electronically.

Both functions according to claim 1 and 2 are based on the fact that the invention switches in parallel to the working circuit, so it is invulnerable before the transient current surges and contact sparks that occur in the working circuit when it is switched on and off. Furthermore, it does operationally safe work in all kinds of operating situations with a fire hazard.

The protection system for electric motors and networks as well as the temperature stabilizer does not have to be built on the switch, its distance from the switch can remain arbitrary. So it is a remote switch and as such it can be used safely in the following cases:

Heat operation (exceptionally warm or cold) Periodic operation Constant operation of the braked rotor.

The invention guarantees the permissible operating heat of the working circuit, so it is operationally suitable for protecting devices, motors, rooms and networks with the risk of explosion.

The protection system for electric motors and networks as well as the temperature stabilizer must already be installed in commissioned equipment and motors.

They are cheap to manufacture, repairable and interchangeable.

Examples:

One way of assembling the protection system against electrical overheating. (A mathematical proof)

Choke - storage choke:

Type . : ZKB - 461/096 - 02 - H2

I _n = 0.63 A; L (at I _n ) = 2500 μH; R = 700 mΩ

Trimmer resistance:

Nominal load 1 W; Temperature range - 55º C to 125º C

Rotation range 270 °; Nominal resistance syirert 2, 2 k Ω relay:

Rated voltage 220 V; Resistance 2900 ± 290 Ω

Switching capacity max. at 250 V ~ 10 kVA

You have to regulate the series circuit so that the relay gets 10, 15, 20% less voltage.

10% 198 V = 0.07 A • 2828 Ω

15% 187 V = 0.07 A • 2671 Ω

20% 176 V = 0.07 A • 2514 Ω. The dimension of the self-induction factor is H (Henry), H = Ω s, the angular frequency is measured in 1 / s, see above

Because of the induction consumer switched into the circuit, we do not have to reckon with the resulting resistance (R), but with impedance (Z) and their self-reciprocal (Y) admittance.

The specific resistance value of the .ϊelais is the inductive reactance, X _L = 3080 Ω R = 700 mΩ + 2200Ω = 2200.7 ≈ 2201 Ω X _L = 2900 ± 290 → 2900 + 180 = 3080 Ω

Of which the impedance or impedance:

Z = 3157.65 Ω = 3158.0 Ω The effective K value of the current:

For the voltage regulation we have the trimmer resistor available, the resistance value of which is changed in such a way that the relay on the voltage of approx. 1-10 V works.

If we want to specify the voltage drop of the network up to 10, 15, 20%, then the voltage is

I. 220 V - 22 V = 198 V

II. 220 V - 33 V = 187 V

III. 220 V - 44 V = 176 V

The magnetic winding binds at approx. 40% voltage drop going on, so

I. 198 V must be reduced by approx. 30% = 59 V.

II. 187 V must be reduced by approx. 25% = 46 V.

III. 176 V must be reduced by approx. 20% = 35 V The resistance values for this reduction are:

I. instead of 2828Ω 1986Ω

II. Instead of 2671Ω 1996Ω

III. instead of 2514Ω 2014Ω

The values proven by mathematical calculation are compensated for by the characteristics of the protective system against electrical overheating, namely it is impossible to determine the parameters of the corresponding components beforehand in the experimental measurements. Likewise, the protection system against electrical overheating must be compensated for because of its internal heating, where the value of each built-in element matches the

Value is changed. Two examples for the operating temperature and voltage drop:

1. The cross section of the line q = 1.5 mm = 1.77 mm, the length of the line 1 - 200 m; I _max = 16 A; U = 220 V The power: P = UI cos ℓ; cos ℓ = 0.8 P = 220 V · 16 A · 0.8 = 2816 W

The resistance value calculated from the power:

The line resistance:

When the line temperature reaches 100ºC, the resistance also increases:

R ₂ = R ₁ [1 + 0.00392 (100-20)] = 2Ω (1 + 0.3136) = 2.63Ω

The resulting voltage drop: U ₁ = I · R · cosℓ = 16 · 2, 63 · 0, 8 = 33.66 V This is 15.3 ≈ 15% of the mains voltage. When the line temperature reaches 60º C, then the resistance: R _2/60 = R ₁ T [1 + 0.00392 (60 - 20)] = 2.31 Ω

_1/60 U = I · R · cos _2/60 ℓ = 16.2,31.0,8 = 29.56 V ≈ 30 V = 13.63%

R = R _w + R _2/60 = 11Ω + 2.31 Ω = 13.31 Ω

U _w = I · R · cosℓ = 16 · 13.31 · 0.8 = 170.37 V ε = 220 - 170.37 V = 49.63 V = 22.6% 2. The length of the line 1 = 200 m; The cross section of the line q = 16 mm ² ; The cable must be loaded with I = 63 A

U = 220 V.

P = UI · cosℓ = 220 · 63 · 0.8 = 110B8 W

The line resistance:

When the line temperature reaches 100º C, the resistance also increases:

R ₂ = 0.22 (1 + 0.00392 x 80) = 0.28Ω

U = I · R · cos ℓ = 63 · 0.28 · 0.8 = 14.11 V = 6.41%

When the line temperature reaches 60 ° C, the resistance R _2/60 = R ₁ [1 + 0.00392 (60 - 20)] = 0.25Ω

U _1/60 = _{IR 2/60} . cosℓ = 63 · 0.25 · 0.8 = 12.6 V = 5.72%

R = R _w + R ₂ = 2.8Ω + 0.25Ω = 3.05Ω

U _w = IR cos = 633.05.0.8 = 153.72 V ε = 220 V - 153.72 V = 66.28 V = 30, 12%

in addition to the permitted load current.

Claims

Protection system for electric motors and networks as well as temperature stabilizer

1. Circuit arrangement for protecting electrical consumers against overload, electrical fire in at least one phase of a multiphase network with a relay for each phase, the excitation winding of which is connected between a conductor carrying the associated phase voltage and reference potential, and via its working contacts in the event of a fault, the emergency switching and an auxiliary circuit causing a malfunction indicator is closed,

characterized,

that for additional protection of the consumer, a series connection of a choke (2) and an adjustable resistor (3) is connected upstream of the excitation winding, which switches off the consumer in the event of undervoltage.

2. Protection system for electric motors and networks as well as temperature stabilizer

characterized,

that the protection system for electric motors and networks according to the preamble of claim 1 can also be used as a temperature stabilizer.

Protection system for electric motors and networks and temperature stabilizer according to claim 1

- characterized in that the protection system for electric motors and networks and temperature stabilizer is a preventive protection connected in parallel to the working circuit, which switches the mains switch by means of the choke (2) connected in series with the relay (4) and adjustable resistor (3) in the event of a fault switches off. - Characterized in that the protection system for electric motors and networks as well as the temperature stabilizer, by its construction, senses the components of the circuit (such as voltage, current, temperature, resistance), so it performs absolutely in the entire field of industry - even when there is a risk of explosion Operational safety

- characterized in that the Arbeitsstrαm dutch does not flow through the protection system for Elektromαtαren and -netze and temperature stabilizer, so it is through the