Shanghai Huabang Industrial Business Network - Frequency relay

[Frequency relay]SQP-6 type underfrequency relay

2026-6-14 10:01:18

Application of SQP-6 Underfrequency Relay
a. Automatically cut off some user loads according to the grid frequency;
b. Automatically disconnect according to frequency in interconnected systems;
c. To ensure the safety of large steam turbine generators or to ensure power supply to important users, disconnect the generator units from the system when the grid frequency decreases;
d. Used in other industrial sectors for power frequency control.
2 Structure and Working Principle
The relay adopts JK-2 housing, and the external dimensions, rear terminals, and installation hole diagram are shown in the appendix. The schematic diagram of the panel is shown in Figure 1. The wiring terminal diagram is shown in Figure 2.

Technical Requirements for SQP-6 Underfrequency Relay
1. The rated value is 100V, 50Hz.
2. The frequency setting error shall not exceed ± 0.0125Hz.
3. The frequency setting range is 45~49.5Hz, and the minimum frequency setting level difference is 0.0125Hz.
4. The return coefficient of underfrequency action shall not exceed 1.002, and the maximum return time shall not exceed 60ms.
5. It is equipped with a normal operation (monitoring) level. When the grid frequency is below 51Hz and the main circuit inside the relay is normal, the normal operation level indicator light will emit a display; If there is a fault in the main circuit inside the relay, the indicator light will turn off (see the previous description of the working principle for the main circuit of the relay).
6. There are two levels of unlocking, the first level is 49.5Hz and the second level is 49.26Hz. When the grid frequency is lower than the selected frequency setting of the unlocking level, the unlocking indicator light will turn on, indicating that the relay underfrequency action circuit is allowed to operate; When the grid frequency is higher than the frequency value selected by the blocking level, the light goes out, indicating that the outlet of the underfrequency action circuit is blocked, preventing the relay from misoperation caused by faults such as transistor breakdown at the outlet due to underfrequency action when the grid frequency is normal.
7. There is a slip locking circuit, and its setting formula is df/dt=K (Hz/s). In the formula, df is the difference between the frequency setting values of the unlocking stage and the underfrequency action stage, and dt has eight levels, namely 0.01, 0.02, 0.04, 0.08, 0.1, 0.2, 0.4, 0.8. dt uses a pulse counting circuit, and K (Hz/s) is selected according to the power grid situation.
8. There is an underfrequency action level, and the underfrequency action frequency setting formula is N=2/fD × 100000. In the formula, fD is the setting frequency, N is the setting value of the finger wheel switch, and a three position finger wheel switch is used for setting. There are two sets of contacts for the 220V DC circuit in the underfrequency action, each with a capacity of 30W.
9. The underfrequency action circuit has a delay, and its delay part adopts a pulse counting circuit. The delay (t) is set to nine levels, which are 0.08, 0.1, 0.15, 0.2, 0.3, 0.5, 15, 20, and 25 seconds respectively. Users can choose according to their needs through the switch.
10. The working range of the input voltage of the relay is AC 60-120V, and below 60V (about 55V), it automatically performs low voltage lockout.
11. Under rated voltage, when the ambient temperature changes within the range of -10~50 ��, the difference between the operating frequency value of any set point of the relay and the operating frequency value under reference conditions shall not exceed ± 0.025Hz.
12. The relay is equipped with 6, 12, and 24V DC stabilized power supplies, which are obtained by rectifying and stabilizing the input voltage signal. Normal power consumption is not greater than 3.5VA, no additional power supply is required.
13. There is a low-frequency test signal inside, and the relay can be manually switched on and off for transmission testing during operation. Before the experiment, disconnect the screen and trip the circuit pressure plate to prevent accidental load switching.
14. The relay is equipped with a central signal contact, with a contact capacity of 220V DC and 30W DC. When there is a fault in the main circuit of the relay, a fault in the under frequency action circuit, or a slip locking situation, an alarm can be triggered through the central signal contact.
15. Not affected by high-order harmonics in the power grid.
16. When the high-frequency interference relay is in the critical state of operation, all input and output circuits should be tested for common state interference using 2.5kV high-frequency oscillation waves, and the AC input circuit should be tested for sulfonic state interference using 1kV high-frequency attenuated oscillation waves, and should not be operated incorrectly or refused to operate.

SQP-6 type underfrequency relay

[Frequency relay]SGP-1 type high-frequency relay

2026-6-14 10:01:10

1 Purpose
SGP-1 high-frequency relay is used in the secondary relay protection lines of high-frequency cutting machines in hydropower plants and power systems, as a sensitive component to respond to frequency increases.
2 Structure and working principle
2.1 The relay adopts JK-2 plug-in housing. The appearance and installation hole size are shown in the appendix, and the back terminal diagram is shown in Figure 1.
2.2 Working principle
This relay is based on T=1/f, and the frequency is reflected by the length of the cycle. The measured AC sine wave is converted into a square wave by an inverter, and the differential circuit converts the square wave into a counting zero spike pulse. The period of the spike pulse is the period of the measured frequency. With the help of a quartz crystal oscillator, a counter is used to calculate how many crystal oscillator cycles there are in a measured cycle. The frequency of this standard cycle is used to set the relay to operate. The following is the description.

Technical requirements for SGP-1 high-frequency relay
3.1 Rated data
Rated voltage 100V; rated frequency 50Hz.
3.2 Range of Action Frequency Setting
50.05~66Hz frequency, allowed to exit above 50.4Hz.
3.3 Return frequency
At rated voltage, the difference between the operating frequency and the return frequency shall not exceed 0.01Hz.
3.4 Voltage Influence
When the measured voltage varies within the range of 60-120V, the difference in operating frequency should not exceed 0.015Hz.
3.5 Action time setting range
The range of action time setting is divided into three types: 0.15~1.5S, 0.3~5S, and 2~20S.
3.6 The return time shall not exceed 70ms.
3.7 Environmental temperature impact
When the ambient temperature varies within the range of -10~+50 ��, the change in operating frequency shall not exceed 0.025Hz.
3.8 Power consumption
Not exceeding 2.5VA at rated voltage.
3.9 Contact Capacity and Contact Form
In a DC inductive load circuit with a voltage not exceeding 220V and a current not exceeding 0.5A (circuit time constant of 5ms ± 15%), 30W can be disconnected. The contact form is two conversions.
3.10 Electrical lifespan
The relay can withstand 5000 actions and still function normally after that.
3.11 Weight
The weight of the relay is about 1.2kg.
4 Debugging Methods
The frequency signal waveform used for debugging is a sine wave, without visible waveform distortion. When using the instrument, accuracy should be considered.
4.1 General Debugging
Set the dial switch to a low frequency value according to the frequency setting method. When changing the measured frequency, the relay should act. Change the setting value of the dial switch, adjust the measured frequency, and the relay should operate at the set point. When the scale is in error, the variable capacitor C7 can be adjusted to operate at the corresponding frequency value, and the frequency setting corresponds to the N number of dial switches (last three digits). If the set frequency is greater than 62.5Hz.
4.2 Low voltage lockout
Low voltage lockout debugging can adjust potentiometer R27. The method is to adjust the measured voltage to 57V, with the measured frequency near the operating frequency, causing the relay to move from operating to non operating, and then increase the voltage at this frequency point, causing the relay to operate. Repeat this process several times to obtain a lockout voltage of 57V.
4.3 Time Debugging
Action time: Open the terminal 5 connector of the base and connect the wires to the terminal as shown in Figure 2. Make the action time consistent with the nameplate data.
Return time: Open the connection piece of terminal 5 on the base and wire the terminal as shown in Figure 3. The return time is 70ms.

4.4 Test circuit debugging
When debugging, as long as the switch is placed in the test position according to the nameplate, the relay will operate within the operating range (but not exit).

[Frequency relay]SZH-2B(SQP-1B/ ��) Digital Frequency Relay

2026-6-13 19:16:27

1. Overview:
1. Automatically cut off some user loads when connected to the power grid frequency; 2. Automatically disconnect according to frequency in interconnected systems; 3. To ensure the safety of large steam turbine generator units or provide power to important users, disconnect the generator units from the system when the grid frequency decreases; 4. Used in other industrial sectors for progressive frequency control.

2. Model parameters:

1. The frequency setting value error shall not exceed ± 0.015Hz, and the minimum frequency setting level difference shall be 0.0125Hz;
2. The frequency setting range is 45-49.7Hz, with one action frequency setting value;
3. The return coefficient is not greater than 1.002, and the return time is not greater than 60ms;
4. The working voltage of the input terminal of the device is AC 60-120V;
5. The setting range for delay action time is 80ms-99.99 seconds, and the maximum setting difference for delay is 10 milliseconds;
6. Preventive measures against misoperation;
Set the range of 45.2-50Hz for releasing frequency lock level setting
Equipped with slip locking circuit, with a setting range of 3-10Hz/S
Equipped with a low voltage lockout circuit for locking below 55V (SQP-1C/II also has a low current lockout);
There is a central alarm signal contact point.
7. Measures to prevent refusal of action:
There is a monitoring level for normal operation, which may trigger an alarm in case of internal faults;
Equipped with low-frequency test signals, transmission tests can be conducted during operation.
8. The operating environment temperature is -25~+50 ��, and the relative humidity does not exceed 90%.
9. There are two pairs of export action contacts and one pair of central alarm signal contacts, both with a capacity of DC220V and 30W.

SZH-2B (SQP-1B/II) digital frequency relay

[Frequency relay]SZH-2A(SQP-1A/ ��) type digital frequency relay

2026-6-13 19:16:19

1. Overview:
1. Automatically cut off some user loads when connected to the power grid frequency; 2. Automatically disconnect according to frequency in interconnected systems; 3. To ensure the safety of large steam turbine generator units or provide power to important users, disconnect the generator units from the system when the grid frequency decreases; 4. Used in other industrial sectors for progressive frequency control.

2. Model parameters:
1. The frequency setting value error shall not exceed ± 0.015Hz, and the minimum frequency setting level difference shall be 0.0125Hz;
2. The frequency setting range is 45-49.7Hz, with one action frequency setting value;
3. The return coefficient is not greater than 1.002, and the return time is not greater than 60ms;
4. The working voltage of the input terminal of the device is AC 60-120V;
5. The setting range for delay action time is 80ms-99.99 seconds, and the maximum setting difference for delay is 10 milliseconds;
6. Preventive measures against misoperation;
Set the range of 45.2-50Hz for releasing frequency lock level setting
Equipped with slip locking circuit, with a setting range of 3-10Hz/S
Equipped with a low voltage lockout circuit for locking below 55V (SQP-1C/II also has a low current lockout);
There is a central alarm signal contact point.
7. Measures to prevent refusal of action:
There is a monitoring level for normal operation, which may trigger an alarm in case of internal faults;
Equipped with low-frequency test signals, transmission tests can be conducted during operation.
8. The operating environment temperature is -25~+50 ��, and the relative humidity does not exceed 90%.
9. There are two pairs of export action contacts and one pair of central alarm signal contacts, both with a capacity of DC220V and 30W.

SZH-2A (SQP-1A/II) Digital Frequency Relay

[Frequency relay]ZSP-1 type digital frequency relay

2026-6-13 19:16:10

rated value		Normal operating voltage	Low current lockout input rated current (A)	Frequency setting range (Hz)	Minimum integer level difference (Hz)	Delay range (s)	low voltage lockout	Low current lockout	Power consumption (VA)		Weight (kg)
Input signal (V)	auxiliary power supply								measurement signal	auxiliary power supply
one hundred two hundred	100V 220V (50Hz)	0.6-1.2 (Ue)	five	39-50	zero point zero one	0.15-25	0.6Ue	0.2le	two	ten	six

ZSP-1 type digital frequency relay

[Frequency relay]BGZ-1B type low cycle rate relay

2026-6-13 18:51:06

1. Overview

The BGZ-1B low cycle rate relay is used as a sensitive component in the secondary relay protection lines of power systems to respond to frequency increases.
2. Institutional characteristics
The BGZ-1B low cycle rate relay is a transistor type with LC series resonance principle. The shell structure adopts standard components JK-2 (protruding rear wiring) and JKF-2Q (protruding front wiring), which must be specified when ordering.

3. Main technical parameters

4. Internal wiring diagram

BGZ-1B type low cycle rate relay

[Frequency relay]BDZ-1B type low cycle rate relay

2026-6-13 18:50:58

1. Overview
The BDZ-1B low cycle rate relay serves as a sensitive element for reducing the response frequency in low cycle load shedding circuits.
2. Institutional characteristics
The BDZ-1B low cycle rate relay is a transistor type with LC series resonance detection principle. The shell structure adopts JK-2 (protruding rear wiring) and JKF-2Q (protruding front wiring) standard components, which must be specified when ordering.

3. Main technical parameters of BDZ-1B low cycle rate relay

4. Internal wiring diagram

BDZ-1B type low cycle rate relay

[Frequency relay]SGP-2/S Digital high-frequency relay

2026-6-13 18:41:10

SGP-2/S digital high-frequency relay

[Frequency relay]SFP-1/S Digital Composite Frequency Relay

2026-6-13 18:41:02

SFP-1/S digital composite frequency relay

[Frequency relay]SQP-2R/S Digital underfrequency relay

2026-6-13 18:40:53

SQP-2R/S digital underfrequency relay

[Frequency relay]SQP-2/S Digital underfrequency relay

2026-6-13 18:40:26

1. Purpose:
SQP-2/S digital underfrequency relay is used as a frequency reduction response element in power grid lines such as load shedding and automatic disconnection according to frequency.

2. Characteristics of SQP-2/S Digital Under Frequency Relay
2.1 Use digital switch direct reading for frequency setting, without the need for formula conversion;
2.2 All digital switches for action frequency, locking frequency, delay frequency, and �� t are installed on the panel for easy setting operation;
2.3 During operation, the digital display shows the normal system frequency. When the relay is activated, the instantaneous system frequency is displayed and locked. Only after pressing the reset button can the normal system frequency be restored.

3. Main technical data
3.1 Frequency setting range: 45-49.99Hz;
3.2 Frequency setting error: not greater than ± 0.015Hz;
3.3 Under frequency action return coefficient not greater than 1.002;
3.4 The return time for low-frequency actions shall not exceed 60ms;
3.5 Under frequency action delay setting range: 0.08-99.9s, with a step difference of 0.01s;
The monitoring level frequency remains constant at 51Hz;
3.7 Locking level frequency setting range: 45-49.99Hz, with a step difference of 0.01Hz;
3.8 Setting range of slip locking circuit: 1-2Hz/s;
3.9 The power at rated voltage and rated frequency shall not exceed 4VA;
3.10 Low voltage lockout setting range: 55-60V.

SQP-2/S digital underfrequency relay