JP2017020954A - Insulation resistance monitoring device in direct current non-grounded electric circuit and monitoring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that an insulation resistance monitoring of a direct current non-grounded electric circuit requires not only an insulation resistance value between an entire electric circuit and a ground, but also the insulation resistance monitoring is required even for each of positive/negative poles since the insulation resistance value of the positive/negative poles placed under the same environment is deteriorated.SOLUTION: An insulation resistance monitoring device connects in series an arbitrary one line of a positive pole side or a negative pole side of a direct current non-grounded electric circuit and a detection resistance body R, and applies rectangular wave signals of a H level and a L level to this resistance body Rfrom rectangular wave signal generation detection means. A both end voltage of the resistance body Rat each level signal is measured when the rectangular wave signal is at the H level and the L level and a line voltage V between the electric circuit are measured so as to be inputted into insulation resistance calculation means. The insulation resistance calculation means is configured to calculate the insulation resistance value between the whole electric circuit and the ground, and the insulation resistance value at the positive pole side and the negative pole side, respectively.SELECTED DRAWING: Figure 1

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.
A detection resistor R ₀ connected between an arbitrary line on the positive electrode side or the negative electrode side of the DC ungrounded circuit and the ground;
Is connected in series with the detection resistor R _0, and for detecting the rectangular wave signal generating means for applying to the detecting resistor R ₀ for detection square wave signal voltage V ₀ which H-level voltage and L level voltage of a constant voltage,
Is connected to both ends of the detecting resistor R _0, and the detection signal voltage measuring means for measuring the voltage across Vr _0,
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 Vr _{0 of} the detection resistor R ₀ and the line voltage V;
A measurement display / alarm means for measuring and displaying the calculation result by the insulation resistance calculation means,
The insulation resistance calculation means includes
A measured value V _H of the line voltage V when the detection rectangular wave signal voltage V ₀ is an H level voltage, and a measured value of the line voltage V when the detection rectangular wave signal voltage V ₀ is an L level voltage. and V _L, and calculates the insulation resistance value R _g between the DC Nonreferenced path across the earth and a measured value of the voltage across the detecting resistor R _0, the positive electrode side insulation resistance R _gp, anode-side insulating characterized by being configured for calculating a DC Nonreferenced path across the positive electrode side insulation resistance from the insulation resistance value R _g between the earth R _gp and the negative insulation resistance R _gn when a resistance value R _gn .

The insulation resistance calculation means in the present invention is characterized in that the insulation resistance value R _g , the negative electrode side insulation resistance value R _gn , and the positive electrode side insulation resistance value R _gp are obtained by the following equations.

R _g = V ₀ × R ₀ / {Vr _0H −Vr _0L × (V _H / V _L )} − R ₀
R _gn = V _L / Vr _0L / (1 / R _g + 1 / R ₀ ) or
R _gn = V _H / {(Vr _0H + V ₀ ) (1 / R _g + 1 / R ₀ ) − (V ₀ / R ₀ )
R _gp = (R _g × R _gn ) / (R _gn −R _g )
Where V ₀ is the value of the detection rectangular wave signal voltage, Vr _0H is the H level voltage of the detection rectangular wave signal voltage, Vr _{0L is} the L level voltage of the detection rectangular wave signal voltage, and R _{0 is the} detection resistor. V _H is a measured value of the line voltage V when the detection rectangular wave signal voltage V _{0 is at} the H level, V _{L is} a line voltage V when the detection rectangular wave signal voltage V _{0 is at} the L level. Measured value of,
When the insulation resistance monitoring method in the present invention is installed between the circuit and the ground of the DC non-grounded circuit, the insulation is monitored.
A detection rectangular wave signal generating means is connected in series with a detection resistor R ₀ connected between an arbitrary line on the positive electrode side or the negative electrode side of the DC ungrounded circuit and the ground,
A detection rectangular wave signal voltage V ₀ is applied to the detection resistor R ₀ from the detection rectangular wave signal generating means to the detection resistor R ₀ as a constant voltage H level voltage and an L level voltage.
The line voltage of the DC ungrounded circuit at the H level and the voltage across the detection resistor R ₀ are measured by the detection signal voltage measuring means, and the detection rectangular wave signal voltage V _{0 is at} the L level. The voltage across the detection resistor R ₀ and the line voltage are detected and input to the insulation resistance calculation means,
The insulation resistance calculation means calculates the insulation resistance value between the entire DC non-grounded circuit and the ground, and calculates the insulation resistance values on the positive and negative sides of the DC non-grounded circuit from the obtained insulation resistance value. The measurement display / alarm means performs measurement display and / or alarm based on the value.

In the present invention, the insulation resistance calculation means
The measurement value V _H of the line voltage V when the detection square wave signal voltage V ₀ is H level, the measured value V _L of the line voltage V when the detection for the rectangular wave signal voltage V ₀ which L level, When the insulation resistance value between the entire DC ungrounded circuit and the ground is R _g , the positive side insulation resistance value R _gp , and the negative side insulation resistance value R _gn , the insulation resistance value is obtained by the following arithmetic expression. And

R _g = V ₀ × R ₀ / {Vr _0H −Vr _0L × (V _H / V _L )} − R ₀
R _gn = V _L / Vr _0L / (1 / R _g + 1 / R ₀ ) or
R _gn = V _H / {(Vr _0H + V ₀ ) (1 / R _g + 1 / R ₀ ) − (V ₀ / R ₀ )
R _gp = (R _g × R _gn ) / (R _gn −R _g )
Where R _{0 is a} detection resistor and the value is known, V _{0 is a} detection rectangular wave signal voltage value, Vr _{0H is a} detection rectangular wave signal voltage H level voltage, and Vr _{0L is a} detection rectangular wave signal. L level voltage of voltage, V _H : Measurement value of line voltage V when detection rectangular wave signal voltage V ₀ is at H level, V _L : Line voltage V when detection rectangular wave signal voltage V ₀ is at L level Measured value of,

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 of the DC non-grounded electric circuit and the ground E through the detection resistor R ₀ . 12 is a detection signal voltage measuring means, connected to both ends of the detecting resistor R ₀ measures the voltage across Vr ₀ to. 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 Vr ₀ and the line voltage, and inputs the output to the measurement display / alarm means 15 to display the measured value and when there is an abnormality. Alarm at.

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 as I _0L = I _nL × R _gp / (R _gp + R ₀ ) (10)
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 / alarm means _R0 ... Detection resistor

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.
A detection resistor R0 connected between an arbitrary line on the positive electrode side or the negative electrode side of the DC ungrounded circuit and the ground;
Connected in series with the detection resistor R0, a rectangular voltage signal voltage V0 having a constant voltage of H level and L level voltage is applied to the detection resistor R0 to generate a voltage Vr0 across the detection resistor R0. and the rectangular wave signal generating means for detecting the cause,
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. Then, the insulation resistance value Rg between the whole DC non-grounded circuit and the ground is calculated from the measured value of the voltage across the detection resistor R0 to obtain the positive side insulation resistance value Rgp and the negative side insulation resistance value Rgn. The positive-side insulation resistance value Rgp and the negative-side insulation resistance value Rgn are calculated from the insulation resistance value Rg between the entire DC ungrounded electric circuit and the ground.

Insulation resistance calculation means of the present invention,
The insulation resistance value Rg is calculated by the equation (3-1), and when the detected rectangular wave signal voltage V0 is measured at the L level using the obtained insulation resistance value Rg, the detection rectangle is obtained by the equation (3-2). When the wave signal voltage V0 is measured at the H level, the negative side insulation resistance value Rgn is calculated by the equation (3-3).
The positive-side insulation resistance value Rgp is calculated by the equation (3-4) when the detection rectangular wave signal voltage V0 is measured at the L level, and
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 ... (3-1)
Rgn = V _L / Vr0 _L / (1 / Rg + 1 / R0) (3-2)
_{Rgn = V H / {(Vr0} H + V0) (1 / Rg + 1 / R0) - (V0 / R0)} ... (3-3)
Rgp = (Rg × Rgn) / (Rgn−Rg) (3-4)
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 high- level voltage of the detection rectangular wave signal voltage , and Vr0 _{L is a} detection rectangular wave signal voltage. L level voltage, R0: detection resistor, value is known, V _H : measurement value of line voltage V when detection rectangular wave signal voltage V0 is at H level, V _L : detection rectangular wave signal voltage V0 Measured value of line voltage V at L level,

When the insulation resistance monitoring method in the present invention is installed between the electric circuit of the DC ungrounded electric circuit and the ground and monitors the insulation,
A detection rectangular wave signal generating means is connected in series with a detection resistor R0 connected between an arbitrary line on the positive electrode side or the negative electrode side of the DC ungrounded circuit and the ground,
A detection rectangular wave signal voltage V0 is applied to the detection resistor R0 from the detection rectangular wave signal generating means to generate a voltage Vr0 across the detection resistor R0 .
The line voltage of the DC ungrounded circuit at the H level and the voltage across the detection resistor R0 are measured by the detection signal voltage measuring means, and the detection rectangular wave signal voltage V0 is at the L level. The voltage across the resistor R0 and the line voltage are detected and input to the insulation resistance calculation means,
The insulation resistance calculation means calculates the insulation resistance value between the entire DC non-grounded circuit and the ground, and calculates the insulation resistance values on the positive and negative sides of the DC non-grounded circuit from the obtained insulation resistance value. Based on the value, the measurement display means performs measurement display and alarm.

Also, the insulation resistance calculation means in the present invention is:
The measured value V _H of the line voltage V when the detection rectangular wave signal voltage V0 from the detection rectangular wave signal generating means is at the H level, and the line voltage when the detection rectangular wave signal voltage V0 is at the L level. When the measured value V _L of V, the insulation resistance value between the entire DC ungrounded circuit and the ground is Rg, the positive side insulation resistance value Rgp, and the negative side insulation resistance value Rgn,
The insulation resistance value Rg is calculated by the equation (4-1), and when the detected rectangular wave signal voltage V0 is measured at the L level using the obtained insulation resistance value Rg, the detection rectangular wave signal is obtained by the equation (4-2). When the voltage V0 is measured at the H level, the negative electrode side insulation resistance value Rgn is calculated by the equation (4-3). The positive electrode side insulation resistance value Rgp is calculated by the equation (4-4) when the detection rectangular wave signal voltage V0 is measured at the L level. While calculating in 4) ,
The measurement display means displays and displays the calculated negative electrode side insulation resistance value Rgn and positive electrode side insulation resistance value Rgp separately or simultaneously .

Rg = V0 × R0 / {Vr0 H -Vr0 L × (V H / V L)} - R0 ... (4-1)
Rgn = V _L / Vr0 _L / (1 / Rg + 1 / R0) (4-2)
_{Rgn = V H / {(Vr0} H + V0) (1 / Rg + 1 / R0) - (V0 / R0)} ... (4-3)
Rgp = (Rg × Rgn) / (Rgn−Rg) (4-4)
Where R0: detection resistor has a known value, V0: detection rectangular wave signal voltage that causes the detection resistor R0 to generate a voltage Vr0 at both ends, and a known value , Vr0H: detection rectangular wave signal voltage H level voltage , Vr0L: L level voltage of the detection rectangular wave signal voltage, VH: Measured value of the line voltage V when the detection rectangular wave signal voltage V0 is H level, VL: When the detection rectangular wave signal voltage V0 is L level Measured value of line voltage V,

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 of the DC non-grounded electric circuit and the ground E through a 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.

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 (4)

In the insulation resistance monitoring device that is installed between the circuit of the DC ungrounded circuit and the ground and monitors insulation,
A detection resistor R ₀ connected between an arbitrary line on the positive electrode side or the negative electrode side of the DC ungrounded circuit and the ground;
Is connected in series with the detection resistor R _0, and for detecting the rectangular wave signal generating means for applying to the detecting resistor R ₀ for detection square wave signal voltage V ₀ which H-level voltage and L level voltage of a constant voltage,
Is connected to both ends of the detecting resistor R _0, and the detection signal voltage measuring means for measuring the voltage across Vr _0,
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 Vr _{0 of} the detection resistor R ₀ and the line voltage V;
A measurement display / alarm means for measuring and displaying the calculation result by the insulation resistance calculation means,
The insulation resistance calculation means includes
A measured value V _H of the line voltage V when the detection rectangular wave signal voltage V ₀ is an H level voltage, and a measured value of the line voltage V when the detection rectangular wave signal voltage V ₀ is an L level voltage. and V _L, and calculates the insulation resistance value R _g between the DC Nonreferenced path across the earth and a measured value of the voltage across the detecting resistor R _0, the positive electrode side insulation resistance R _gp, anode-side insulating and characterized by being configured so as to calculate the DC Nonreferenced path across the positive electrode side insulation resistance from the insulation resistance value R _g between the earth R _gp and the negative insulation resistance R _gn when a resistance value R _gn Insulation resistance monitoring device for DC ungrounded circuit. 2. The insulation in a DC ungrounded circuit according to claim 1, wherein the insulation resistance calculation means obtains an insulation resistance value R _g , a negative electrode side insulation resistance value R _gn , and a positive electrode side insulation resistance value R _gp by the following equations. Resistance monitoring device.
R _g = V ₀ × R ₀ / {Vr _0H −Vr _0L × (V _H / V _L )} − R ₀
R _gn = V _L / Vr _0L / (1 / R _g + 1 / R ₀ ) or
R _gn = V _H / {(Vr _0H + V ₀ ) (1 / R _g + 1 / R ₀ ) − (V ₀ / R ₀ )
R _gp = (R _g × R _gn ) / (R _gn −R _g )
Where V ₀ is the value of the detection rectangular wave signal voltage, Vr _0H is the H level voltage of the detection rectangular wave signal voltage, Vr _{0L is} the L level voltage of the detection rectangular wave signal voltage, and R _{0 is the} detection resistor. V _H is a measured value of the line voltage V when the detection rectangular wave signal voltage V _{0 is at} the H level, V _{L is} a line voltage V when the detection rectangular wave signal voltage V _{0 is at} the L level. Measured value of, In the insulation resistance monitoring method that is installed between the circuit of the DC ungrounded circuit and the ground and monitors insulation,
A detection rectangular wave signal generating means is connected in series with a detection resistor R ₀ connected between an arbitrary line on the positive electrode side or the negative electrode side of the DC ungrounded circuit and the ground,
A detection rectangular wave signal voltage V ₀ is applied to the detection resistor R ₀ from the detection rectangular wave signal generating means to the detection resistor R ₀ as a constant voltage H level voltage and an L level voltage.
The line voltage of the DC ungrounded circuit at the H level and the voltage across the detection resistor R ₀ are measured by the detection signal voltage measuring means, and the detection rectangular wave signal voltage V _{0 is at} the L level. The voltage across the detection resistor R ₀ and the line voltage are detected and input to the insulation resistance calculation means,
The insulation resistance calculation means calculates the insulation resistance value between the entire DC non-grounded circuit and the ground, and calculates the insulation resistance values on the positive and negative sides of the DC non-grounded circuit from the obtained insulation resistance value. A method for monitoring insulation resistance in a DC non-grounded electric circuit, wherein measurement display / alarm means is used for measurement display / alarm based on the value. The insulation resistance calculation means includes
The measurement value V _H of the line voltage V when the detection square wave signal voltage V ₀ is H level, the measured value V _L of the line voltage V when the detection for the rectangular wave signal voltage V ₀ which L level, When the insulation resistance value between the entire DC ungrounded circuit and the ground is R _g , the positive side insulation resistance value R _gp , and the negative side insulation resistance value R _gn , the insulation resistance value is obtained by the following arithmetic expression. The insulation resistance monitoring method in the DC ungrounded circuit according to claim 3.
R _g = V ₀ × R ₀ / {Vr _0H −Vr _0L × (V _H / V _L )} − R ₀
R _gn = V _L / Vr _0L / (1 / R _g + 1 / R ₀ ) or
R _gn = V _H / {(Vr _0H + V ₀ ) (1 / R _g + 1 / R ₀ ) − (V ₀ / R ₀ )
R _gp = (R _g × R _gn ) / (R _gn −R _g )
Where R _{0 is a} detection resistor and the value is known, V _{0 is a} detection rectangular wave signal voltage value, Vr _{0H is a} detection rectangular wave signal voltage H level voltage, and Vr _{0L is a} detection rectangular wave signal. L level voltage of voltage, V _H : Measurement value of line voltage V when detection rectangular wave signal voltage V ₀ is at H level, V _L : Line voltage V when detection rectangular wave signal voltage V ₀ is at L level Measured value of,

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