Insulation monitor relays

1. Overview

UBCS1 model product is a DC insulation monitoring device based on the MODBUS protocol, including DC ground insulation resistance monitoring, DC voltage monitoring, DC voltage reverse connection alarm and other safety monitoring functions. It can be used in DC systems below 1000V such as EV DC charging systems, photovoltaic systems, energy storage systems, and DC grids. This product has the insulation monitoring start-stop function. After the insulation monitoring is started, it can monitor the insulation resistance of the positive and negative electrodes to the ground in real time. The monitoring results are not affected by DC voltage fluctuations, and are not affected by the symmetry of the positive and negative insulation resistance.

2. interface and function

2.1 Insulation monitoring function

This product can send communication frames through RS485 to turn on or off the insulation monitoring function. After the insulation monitoring function is turned on, the high-voltage grounding switch K is closed to realize real-time measurement of insulation resistance. After the insulation monitoring function is turned off, the high-voltage grounding switch K is turned off. The opening and closing of the insulation monitoring only determines whether the insulation resistance monitoring is turned on, and does not affect the DC voltage monitoring. After the product is powered, the DC voltage is in a state of continuous monitoring.

After the insulation monitoring function is turned on, the product continues to monitor the insulation resistance in real time, and the user can read the insulation resistance value as soon as 1 second after the insulation monitoring function is turned on. For the presence of DC-to-ground capacitance, the module can realize self-adaptive monitoring of ground capacitance below 3uF (the positive and negative poles to ground capacitance are respectively below 3uF, and the total capacitance is below 6uF). When there is a ground-to-ground capacitance, the monitoring time is ≤2.5 s.

2.2 LED light display

The 'PWR' light is on after the module is powered on, the 'LD1' light is on after the insulation resistance monitoring function is turned on, and the 'LD1' light is off after the insulation resistance monitoring function is turned off.

2.3 RS485 communication

Users can send and receive data frames through the RS485 communication port, and the circuit is equipped with a 510Ω terminal resistor. The specific operation method can be found in the "communication protocol". Terminals A and B correspond to A and B output by RS485 respectively.

2.4 Communication parameter configuration bits

The DIP switch is used to configure the communication parameters, 1 bit is used to set the baud rate, 2-4 bits are used to set the communication address, and 5 and 6 bits are used to set the parity check.

3. Wiring Method

 4. structure parameter

GYDCG-UBCS1, with shell model, can be mounted by DIN rail or fixed by screws. The standard width of DIN rail is 35mm. Dimensions are shown as follows: (Unit: mm)

5. Electrical Parameters

① When the difference between the positive-to-ground insulation resistance R_ISO+ and the negative-to-ground insulation resistance R_ISO- is too large, and the difference is greater than 5 times, the large resistance of R_ISO+ and R_ISO- may not meet the typical value.

② C_Y refers to the Y capacitance value of the positive and negative of the system bus to the ground respectively.

6. communication protocol

This device provides Modbus RTU protocol interface, using Modbus RTU 0x03/0x06 command; baud rate, communication address, parity check mode, can be set by dial switch, stop bit 1, data bit 8. The time interval between each byte in the sending frame must not exceed 20ms, otherwise the frame will be cleared.

This module works in slave mode.