JP6220821B2 - Insulation resistance monitoring device and monitoring method in DC ungrounded circuit - Google Patents

Description

  The present invention relates to an insulation resistance monitoring device and a monitoring method in a DC non-grounded electric circuit.

Patent Document 1 is known as an insulation resistance detection device in a DC ungrounded circuit. FIG. 6 shows an equivalent circuit of the insulation resistance detection device disclosed in Patent Document 1. Between direct current ungrounded circuit connected to the solar cell and ground E, direct currents having different voltage values from V ₁ and V ₂ are shown. The power supplies are connected separately via resistors Rd ₁ and Rd ₂ , respectively. The connected DC power source is alternately switched between the V ₁ side and the V ₂ side by the changeover switch S, and a voltage is applied to the resistor. The insulation between the DC non-grounded circuit and the ground E is determined from the amount of change in the current due to the applied voltage difference. Seeking resistance.

JP2013-33827A

  The insulation resistance value obtained in Patent Document 1 is an insulation resistance value between the entire DC non-grounded circuit and the ground E, and is an insulation resistance for each one side of the positive or negative side of the DC non-grounded circuit. I didn't ask for a value. Therefore, when the insulation resistance detection device is set to issue an alarm when the insulation resistance value of either one of the positive and negative electrodes, or both of the electrode sides becomes 100 kΩ or less, the positive electrode side or the negative electrode side is When the insulation resistance value decreases to 200 kΩ in both cases, the obtained insulation resistance value becomes a combined value of the positive and negative electrodes and becomes 100 kΩ, and an alarm is issued earlier than the set value.

  The fact that the insulation resistance values of the positive and negative poles of the DC ungrounded circuit are deteriorated substantially simultaneously is a problem that can occur sufficiently because both the positive and negative poles are placed in the same environment. Moreover, in patent document 1, since it measures by switching a direct-current applied voltage, a difference arises in measurement time. Within this time difference, there is a problem that even if the voltage of the DC ungrounded circuit is slightly changed, a large error occurs in the insulation resistance value, and accurate detection cannot be performed.

  The purpose of the present invention is to eliminate the DC power source switching means, and to measure both the positive and negative poles of the DC non-grounded circuit, and simultaneously measure both poles, enabling accurate measurement and monitoring of the insulation resistance value. An object of the present invention is to provide an insulation resistance monitoring device and a monitoring method for a direct current ungrounded circuit.

The present invention is an insulation resistance monitoring device that is installed between a circuit of a DC non-grounded circuit and the ground and monitors insulation.
The detection resistor R0 is connected between any one of the positive and negative electrodes of the DC non-grounded circuit and the ground, and the detection resistor R0 has a constant H level voltage and an L level voltage at both ends. A detection rectangular wave signal generating means for applying a detection rectangular wave signal voltage V0 to generate a voltage Vr0 at both ends of the detection resistor R0;
Detection signal voltage measuring means connected to both ends of the detection resistor R0 and measuring the voltage Vr0 at both ends;
A line voltage detecting means for measuring a line voltage V of the DC ungrounded circuit;
Insulation resistance calculation means for calculating an insulation resistance value by inputting the measured both-ends voltage Vr0 of the detection resistor R0 and the line voltage V;
Comprising measurement display means for measuring and displaying the calculation result by the insulation resistance calculation means,
The insulation resistance calculation means includes
The measured value V _H of the line voltage V when the detection rectangular wave signal voltage V0 is the H level voltage, and the measured value V _L of the line voltage V when the detection rectangular wave signal voltage V0 is the L level voltage. And an insulation resistance value Rg between the whole DC non-grounded electric circuit and the ground from the measured values Vr0 _H and Vr0 _{L of the} voltage Vr0 across the detection resistor R0 by the equation (1-1),
Using the obtained insulation resistance value Rg, when the detection rectangular wave signal voltage V0 is L level measurement, the equation (1-2) is used. When the detection rectangular wave signal voltage V0 is H level measurement, the equation (1-3) is used. To calculate the negative side insulation resistance value Rgn respectively.
The positive side insulation resistance value Rgp is calculated by the equation (1-4) when the detection rectangular wave signal voltage V0 is L level measurement,
The measurement display means is configured to measure and display the negative electrode side insulation resistance value Rgn and the positive electrode side insulation resistance value Rgp separately or both at the same time.
Rg = V0 × R0 / {Vr0 H -Vr0 L × (V H / V L)} - R0 ... (1-1)
Rgn = V _L / Vr0 _L / (1 / Rg + 1 / R0) (1-2)
_{Rgn = V H / {(Vr0} H + V0) (1 / Rg + 1 / R0) - (V0 / R0)} ... (1-3)
Rgp = (Rg × Rgn) / (Rgn−Rg) (1-4)
Where V0 is a detection rectangular wave signal voltage for generating a voltage Vr0 across the detection resistor R0, and the value is known, Vr0 _H is a voltage across the detection resistor R0 when the detection rectangular wave signal voltage is at an H level voltage. Vr0 _L : Measured value of the voltage across the detection resistor at the L level voltage of the detection rectangular wave signal voltage, R 0: Known value at the detection resistor, V _H : Detection rectangular wave signal voltage measured value of the line voltage V H level when V0, V _L: measured value of the line voltage V at L level detection square wave signal voltage V0

The present invention is an insulation resistance monitoring method for monitoring insulation by being installed between a circuit and a ground of a DC non-grounded circuit,
A detection rectangular wave signal generating means in which a detection resistor R0 is connected in series is connected between an arbitrary line on the positive electrode side or negative electrode side of the DC non-grounded circuit and the ground, and from the detection rectangular wave signal generating means The detection resistor R0 is applied with a detection rectangular wave signal voltage V0 based on a constant H level voltage and an L level voltage to generate a voltage Vr0 at both ends of the detection resistor R0.
Input the line voltage V of the DC ungrounded circuit and the voltage Vr0 across the detection resistor R0 into the insulation resistance calculation means,
In the insulation resistance calculation means,
Measured value V _L during resulting line voltage V when the measured value V _H of the line voltage V, the detection square wave signal voltage V0 is at the L level when the detection square wave signal voltage V0 is H level voltage From the measured values Vr0 _H and Vr0 _{L of the} both-end voltage Vr0, the insulation resistance value Rg between the entire DC non-grounded circuit and the ground is calculated by the equation (2-1),
Using the obtained insulation resistance value Rg, when the detection rectangular wave signal voltage V0 is measured at the L level, the equation (2-2) is used. When the detection rectangular wave signal voltage V0 is measured at the H level, the equation (2-3) is used. To calculate the negative side insulation resistance value Rgn respectively.
The positive-side insulation resistance value Rgp is calculated by the equation (2-4) when the detection rectangular wave signal voltage V0 is L level voltage measurement,
The negative electrode side insulation resistance value Rgn and the positive electrode side insulation resistance value Rgp of the calculation result are measured and displayed by a measurement display means .
Rg = V0 × R0 / {Vr0 H -Vr0 L × (V H / V L)} - R0 ... (2-1)
Rgn = V _L / Vr0 _L / (1 / Rg + 1 / R0) (2-2)
_{Rgn = V H / {(Vr0} H + V0) (1 / Rg + 1 / R0) - (V0 / R0)} ... (2-3)
Rgp = (Rg × Rgn) / (Rgn−Rg) (2-4)
However, R0: detection resistor has a known value, V0: detection resistor R0 generates a voltage Vr0 at both ends, and the value is known, Vr0 _H : detection rectangular wave signal voltage H level measured value of the voltage across the detecting resistor R0 when voltage, Vr0 _L: measured value of the voltage across the detecting resistor R0 when L-level voltage of the detection square wave signal voltage, V _H: detection square wave signal measured value of the line voltage V at the H level voltage V0, V _L: measured value of the line voltage V at L level detection square wave signal voltage V0

As described above, according to the present invention, the following effects can be obtained.
(1) As a detection signal for insulation monitoring between the circuit of the DC non-grounded circuit and the ground,
By applying a rectangular wave signal via the detection resistor R ₀ between the positive electrode side or negative electrode side of the DC ungrounded circuit and the ground, a switching means for the DC power supply as in Patent Document 1 is required. Therefore, the apparatus configuration is simplified.
(2) It is possible to accurately detect the insulation resistance value on either the positive electrode side or the negative electrode side of the DC non-grounded circuit, and the insulation resistance value when both electrodes are simultaneously deteriorated.
(3) Even if the voltage of the DC non-grounded circuit during measurement changes, it is possible to accurately measure the insulation resistance value.

The block diagram which shows embodiment of this invention. It is an equivalent circuit for explanation, (a) is an equivalent circuit, (b) is a rectangular wave signal voltage for detection. An equivalent circuit, (a) is an equivalent circuit at the H level (T ₁ ), and (b) is an equivalent circuit at the L level (T ₂ ). Equivalent circuit when assuming the H level (T ₁ ) without the circuit voltage source. It is explanatory drawing at the time of the presence or absence of the fluctuation | variation of a line voltage, (a) is no fluctuation, (b) There is a fluctuation. The block diagram of the conventional insulation resistance monitoring apparatus.

FIG. 1 shows a configuration diagram of an insulation resistance monitoring device 10 in a DC non-grounded electric circuit showing an embodiment of the present invention. Reference numeral 11 denotes a detection rectangular wave signal generating means, which is connected between the positive electrode side P and the ground E of the DC non-grounded electric circuit via the detection resistor R0. A detection signal voltage measuring means 12 is connected to both ends of the detection resistor R0 and measures a both-end voltage Vr0. Reference numeral 13 denotes a line voltage detecting means for detecting a line voltage V between the positive electrode side P and the negative electrode side N of the direct current ungrounded circuit. 14 is an insulation resistance calculation means, which calculates the insulation resistance value by inputting the measured both-end voltage Vr0 and the line voltage, and inputs the output to the measurement display means 15 to display the measured value and alarm in case of abnormality. I do.

1 is a circuit voltage source having a line voltage V, 2 is a positive side P of a DC non-grounded circuit, 3 is a negative side N of the DC non-grounded circuit, R _gp is a positive side insulation resistance, and R _gn is a negative side The side insulation resistance, V _0, is a detection rectangular wave signal voltage.

FIG. 2 shows an equivalent circuit for explanation. As shown in FIG. 2A, the detection rectangular wave signal generating means 11 is a detection rectangular wave signal generated for the detection resistor R ₀ . A voltage V ₀ is applied. The detection signal voltage measuring means 12 includes a line voltage V _H when the H level (T ₁ ) of the rectangular wave signal is applied and a detection resistor at that time, as shown in FIG. The voltage Vr _0H across R ₀ is measured. Next, the line voltage V _L when the L level (T ₂ ) of the rectangular wave signal is applied and the voltage Vr _0L across the detection resistor R ₀ at that time are measured, and each measured value is calculated as an insulation resistance. Output to means 14.

3A shows an equivalent circuit when the rectangular wave signal is at the H level (T ₁ ), and FIG. 3B shows an equivalent circuit when the rectangular wave signal is at the L level (T ₂ ). However, if there is no fluctuation in the line voltage V when measuring the rectangular wave signal levels (T ₁ ) and (T ₂ ), V = V _H = V _L. When the rectangular wave signal in FIG. 3A is at the H level (T ₁ ), the currents flowing through the resistors R _gn , R _gp , and R ₀ are I _nH , I _pH , and I _0H , _respectively , and the rectangular wave in FIG. signal to the respective current when the L-level _{(T 2) I nL, I} pL, and I _0L.

Next, assuming that there is no line voltage V, the equivalent circuit when the detection rectangular wave signal voltage V ₀ is at the H level (T ₁ ) is shown in FIG. 4, and the resistors R _gn , R _gp , R at that time _Assuming that the currents flowing in ₀ are I _nf , I _pf , and I _0f , _respectively , currents I _nH , I _pH , when the detection rectangular wave signal voltage V ₀ is at the H level (T ₁ ) with the line voltage V _H. I _0H is expressed by equations (1) to (3) based on the principle of superposition.
I _nH = I _nL + I _nf (1)
I _pH = I _pL + I _pf (2)
I _0H = I _0L + I _0f (3)
I _0H and I _0L can be obtained from equations (4) and (5) by measuring the voltages Vr _0H and Vr _0L across the detection resistor R ₀ .
I _0H = Vr _0H / R ₀ (4)
I _0L = Vr _0L / R ₀ (5)
The current I _0f flowing through the detection resistor R ₀ is calculated from the equations (3), (4), and (5) as follows: I _0f = I _0H −I _0L = Vr _0H / R ₀ −Vr _0L / R ₀ = (Vr _0H −Vr _0L ) / R ₀ (6)
It becomes.
I _0f can be regarded as a current flowing through the detection resistor R ₀ when it is assumed that there is no line voltage V and the detection rectangular wave signal voltage V ₀ is at the H level (T ₁ ).
V ₀ −R ₀ × I _0f −R _g × I _0f = 0 (7)
And
The parallel combined resistance R _g = R _gp × R _gn / (R _gp + R _gn ) of the positive electrode side insulation resistance R _gp and the negative electrode side insulation resistance R _gn is obtained from the equations (6), (7) to (8). .
R _g = V ₀ / I _0f −R ₀ = V ₀ × R ₀ / (Vr _0H −Vr _0L ) −R ₀ (8)
Next, when the detection rectangular wave signal voltage V ₀ is H level (T ₁ ), the line voltage is V _H , and when the detection rectangular wave signal voltage V ₀ is L level (T ₂ ), the line voltage is V _If it changes to _L , an error will occur at that time. The equivalent circuit at that time is shown in FIG. 5 and will be explained by the following calculation.

I _nL when the detection square wave signal voltage V ₀ there is no variation in the line voltage V when measuring the L level _{(T 2) (V = V} H = V L) is
_{I nL = V L / {R} gn + (R gp × R 0) / (R gp + R 0)} ... (9)
Thus, the current I _0L flowing through the detection resistor R ₀ is expressed by I _0L = I _nL × R _gp / (R _gp + R ₀ ) (10) according to the law of shunting.
It becomes.

The line voltage V at the time of measurement varies, and the current _InLX when the line voltage at that time is V _LX is
_{I nLX = V LX / {R} gn + (R gp × R 0) / (R gp + R 0)} ... (11)
Thus, the current I _0LX flowing through the detection resistor R ₀ is I _0LX = _InLX × R _gp / (R _gp + R ₀ ) (12) according to the law of shunting.
Next, I the equation _{(9) ~ (12) 0L} / I 0LX = I nL / I nLX = V L / V LX
I _0L = I _0LX × (V _L / V _LX )
V _L when there is no fluctuation in the line voltage V is V _L = V _H , so both sides are multiplied by R ₀ ,
R ₀ × I _0L = R ₀ × I _0LX × (V _H / V _LX )
Vr _0L = Vr _0LX × (V _H / V _LX )
Thus, the value of Vr _0L before the line voltage V fluctuates can be obtained by multiplying the value of Vr _0LX detected when the line voltage V fluctuates by (V _H / V _LX ). Since V _LX and Vr _0LX are V _L and Vr _0L measured at the time of line voltage fluctuation, Equation (8) can be changed to R _g = V ₀ × R ₀ / {Vr _0H −Vr _0L × (V _H / V _L )}-R ₀ (13)
By doing so, the error at the time of line voltage fluctuation can be eliminated.

Next, R _gp and R _gn are respectively obtained from values at the time when the rectangular wave signal is measured at the L level (T ₂ ). In the case of FIG. 3B, the voltage V _pe between the positive electrode side P of the DC ungrounded circuit and the ground E is V _pe = (V _L / R _gn + 0 / R _gp + 0 / R ₀ , using Milman's theorem. ) / (1 / R _gn + 1 / R _gp + 1 / R ₀ )
= (V _L / R _gn ) / (1 / R _g + 1 / R ₀ ) (14)
Can be expressed by, detecting resistor R ₀ is known, the line voltage V _L is measured in the line voltage detecting unit 13, also the voltage across the V _pe = detecting resistor at Vr _0L R ₀ is It is measured by the detection signal voltage measuring means 12.

In the insulation resistance computing means 14, a DC Nonreferenced path across the insulation resistance value R _g between the earth because it is determined by the formula (13), wherein the negative electrode side insulation resistance R _gn (14) from equation (15) Ask for.
R _gn = V _L / Vr _0L / (1 / R _g + 1 / R ₀ ) (15)
Therefore, the positive-side insulation resistance value / R _gp is
R _gp = (R _g × R _gn ) / (R _gn −R _g ) (16)
Can be obtained.

In the above description, the method for obtaining the detection rectangular wave signal voltage V ₀ from the value at the time of measurement of the L level (T ₂ ) has been described, but it can also be obtained from the value at the time of measurement of the H level (T ₁ ). In addition, the arithmetic expression of the negative electrode side insulation resistance value R _gn is given by Expression (17). Similarly, the positive electrode side insulation resistance value R _gp is obtained by the equation (16).
R _gn = V _H / {(Vr _0H + V ₀ ) (1 / R _g + 1 / R ₀ ) − (V ₀ / R ₀ ) (17)
1 shows a case where the detection rectangular wave signal generating means 11 is connected between the positive electrode side P of the DC non-grounded electric circuit and the ground E, the detection rectangular wave signal generating means 11 is a negative electrode. You may connect between side N and ground E. In that case, it is the same as the polarity of the line voltage V of the electric circuit shown in FIG. 2A is reversed, and by changing the signs R _gn and R _gn of the equations (15), (16) and (17), It can be obtained in the same way.

  In FIG. 2B, the H level of the rectangular wave signal generated by the detection rectangular wave signal generating means 11 is a positive voltage and the L level is zero volts, but the H level is zero volts and the L level is a negative voltage. Good. In addition, although the detection rectangular wave signal generation circuit and the calculation are complicated, the insulation resistance value can be obtained even if the rectangular wave signal has a constant voltage value at each of the H level and the L level.

DESCRIPTION OF SYMBOLS 10 ... Insulation resistance monitoring apparatus 11 ... Detection rectangular wave signal generation means 12 ... Detection signal voltage measurement means 13 ... Line voltage detection means 14 ... Insulation resistance calculation means 15 ... Measurement display means R0 ... Detection resistor

Claims (2)

In the insulation resistance monitoring device that is installed between the circuit of the DC ungrounded circuit and the ground and monitors insulation,
The detection resistor R0 is connected between any one of the positive and negative electrodes of the DC non-grounded circuit and the ground, and the detection resistor R0 has a constant H level voltage and an L level voltage at both ends. A detection rectangular wave signal generating means for applying a detection rectangular wave signal voltage V0 to generate a voltage Vr0 at both ends of the detection resistor R0;
Detection signal voltage measuring means connected to both ends of the detection resistor R0 and measuring the voltage Vr0 at both ends;
A line voltage detecting means for measuring a line voltage V of the DC ungrounded circuit;
Insulation resistance calculation means for calculating an insulation resistance value by inputting the measured both-ends voltage Vr0 of the detection resistor R0 and the line voltage V;
Comprising measurement display means for measuring and displaying the calculation result by the insulation resistance calculation means,
The insulation resistance calculation means includes
The measured value V _H of the line voltage V when the detection rectangular wave signal voltage V0 is the H level voltage, and the measured value V _L of the line voltage V when the detection rectangular wave signal voltage V0 is the L level voltage. And an insulation resistance value Rg between the whole DC non-grounded electric circuit and the ground from the measured values Vr0 _H and Vr0 _{L of the} voltage Vr0 across the detection resistor R0 by the equation (1-1),
Using the obtained insulation resistance value Rg, when the detection rectangular wave signal voltage V0 is L level measurement, the equation (1-2) is used. When the detection rectangular wave signal voltage V0 is H level measurement, the equation (1-3) is used. To calculate the negative side insulation resistance value Rgn respectively.
The positive side insulation resistance value Rgp is calculated by the equation (1-4) when the detection rectangular wave signal voltage V0 is L level measurement, and
An insulation resistance monitoring device in a DC non-grounded electric circuit, wherein the measurement display means displays and displays the negative electrode side insulation resistance value Rgn and the positive electrode side insulation resistance value Rgp separately or simultaneously on both electrodes.
Rg = V0 × R0 / {Vr0 H -Vr0 L × (V H / V L)} - R0 ... (1-1)
Rgn = V _L / Vr0 _L / (1 / Rg + 1 / R0) (1-2)
_{Rgn = V H / {(Vr0} H + V0) (1 / Rg + 1 / R0) - (V0 / R0)} ... (1-3)
Rgp = (Rg × Rgn) / (Rgn−Rg) (1-4)
Where V0 is a detection rectangular wave signal voltage for generating a voltage Vr0 across the detection resistor R0, and the value is known, Vr0 _H is a voltage across the detection resistor R0 when the detection rectangular wave signal voltage is at an H level voltage. Vr0 _L : Measured value of the voltage across the detection resistor at the L level voltage of the detection rectangular wave signal voltage, R 0: Known value at the detection resistor, V _H : Detection rectangular wave signal voltage measured value of the line voltage V H level when V0, V _L: measured value of the line voltage V at L level detection square wave signal voltage V0 An insulation resistance monitoring method that is installed between a DC ungrounded circuit and the ground to monitor insulation,
A detection rectangular wave signal generating means in which a detection resistor R0 is connected in series is connected between an arbitrary line on the positive electrode side or negative electrode side of the DC non-grounded circuit and the ground, and from the detection rectangular wave signal generating means A detection rectangular wave signal voltage V0 based on a constant H level voltage and L level voltage is applied to the detection resistor R0 to generate a voltage Vr0 at both ends of the detection resistor R0.
The line voltage V of the DC ungrounded circuit and the voltage Vr0 across the detection resistor R0 are input to the insulation resistance calculation means,
In the insulation resistance calculation means,
Measured value V _L during resulting line voltage V when the measured value V _H of the line voltage V, the detection square wave signal voltage V0 is at the L level when the detection square wave signal voltage V0 is H level voltage From the measured values Vr0 _H and Vr0 _{L of the} both-end voltage Vr0, the insulation resistance value Rg between the entire DC non-grounded circuit and the ground is calculated by the equation (2-1),
Using the obtained insulation resistance value Rg, when the detection rectangular wave signal voltage V0 is L level voltage, the equation (2-2) is used. When the detection rectangular wave signal voltage V0 is H level voltage, the equation (2- 3) In each case, the negative side insulation resistance value Rgn is calculated,
The positive-side insulation resistance value Rgp is calculated by the equation (2-4) when the detection rectangular wave signal voltage V0 is L level voltage measurement,
An insulation resistance monitoring method for a DC non-grounded electric circuit, characterized in that the negative electrode side insulation resistance value Rgn and the positive electrode side insulation resistance value Rgp are measured and displayed by a measurement display means .
Rg = V0 × R0 / {Vr0 H -Vr0 L × (V H / V L)} - R0 ... (2-1)
Rgn = V _L / Vr0 _L / (1 / Rg + 1 / R0) (2-2)
_{Rgn = V H / {(Vr0} H + V0) (1 / Rg + 1 / R0) - (V0 / R0)} ... (2-3)
Rgp = (Rg × Rgn) / (Rgn−Rg) (2-4)
However, R0: detection resistor has a known value, V0: detection resistor R0 generates a voltage Vr0 at both ends, and the value is known, Vr0 _H : detection rectangular wave signal voltage H level measured value of the voltage across the detecting resistor R0 when voltage, Vr0 _L: measured value of the voltage across the detecting resistor R0 when L-level voltage of the detection square wave signal voltage, V _H: detection square wave signal measured value of the line voltage V at the H level voltage V0, V _L: measured value of the line voltage V at L level detection square wave signal voltage V0

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