Generator Synchronization Panel ANSI(25/25A/27/59/81)

Description

Overview of Generator Synchronization Panel

• The generator synchronization panel (also known as a synchronization panel, synchronizing panel, or synchronization control panel) is the core operational, monitoring, and control equipment used in power systems—such as power plants, substations, marine power plants, and isolated power plants—to enable generator units to operate in synchronous parallel with the power grid (or another generator).

Conditions for connecting a generator to the grid for parallel operation

No.	Parallel Condition	Description
1	Equal Voltage	The amplitude of generator terminal voltage shall be equal to that of power grid (system) voltage or within the allowable deviation range.
2	Identical Frequency	The frequency of generator shall be consistent with power grid frequency or within the allowable deviation range.
3	Consistent Phase Sequence	The phase sequence of generator must be strictly identical with that of power grid. This is an absolute prerequisite without any deviation allowed.

• Of the three conditions mentioned above, phase sequence consistency is a non-negotiable, mandatory requirement; while voltage and frequency deviations are permitted to a certain extent, they must be kept within safe thresholds.
• In the actual grid-synchronization process, voltage, frequency, and phase deviations cannot be absolutely zero.
• The core function of the generator synchronizing panel is to monitor deviations in these three parameters in real time and, when the deviations fall within the permissible range, to issue a closing command safely and accurately, enabling the generating unit to synchronize smoothly with the grid.

Generator synchronizing panel schematic

Steps for automatic synchronization of generator in the control panel

Testing of the Automatic Synchronization Device

Step	Content
a	Power on the device, check self-inspection and initialization status to confirm normal operation.
b	Modify setting values according to on-site conditions: switch closing time, allowable frequency difference, allowable voltage difference, frequency regulation control coefficient, voltage regulation control coefficient, single-side no-voltage closing permission, etc.
c	Select each synchronization point via selection switch; the device shall display the corresponding synchronization point number.
d	Carry out automatic synchronization closing test at any synchronization point to verify whether the device outputs synchronization closing command correctly.
e	Apply grid-connected required voltage to system side and standby side respectively, check if the collected and displayed voltage and frequency are consistent with external actual values.
f	Keep voltage and frequency of system side stable, change parameters of standby side, and verify correct action of four output relays: speed increase, speed decrease, voltage rise and voltage drop.
g	Adjust voltage and frequency of both sides within closing setting range; the device shall send out closing command, the closing indicator light turns on, and the closing contact on terminal block conducts.

Generator Synchronization Panel and Its System Dynamic Test

Step	Content	Key Requirements
a	Manual Synchronous Closing Test	Adjust applied voltage parameters to meet synchronization conditions, operate closing control switch, and ensure circuit breaker closes normally.
b	Manual Asynchronous Closing Test	Operate closing switch when parameters fail to meet synchronization conditions; the closing operation shall be blocked to verify the blocking function.
c	Automatic Precise Synchronization Closing Test	After parameters meet the requirements, the automatic synchronization device shall output closing command automatically and the circuit breaker closes properly.
d	Manual Simulated Grid-connection Test	Open generator outlet isolating switch, build up generator voltage and switch on manual synchronization circuit, adjust voltage and frequency to qualified values then perform manual closing.
e	Automatic Simulated Grid-connection Test	Open the isolating switch, establish generator voltage and activate automatic synchronization circuit. The device shall conduct automatic regulation and send closing command once all conditions are satisfied.

Generator synchronization panel price

• The price of a generator synchronizing panel typically ranges from 30,000 to 50,000 RMB, depending on the specific technical specifications.

Key Technical Specifications

Parameter	Typical Range / Requirement	Description
Input Power Supply	AC 85V～250V / DC 100V～250V	Shall match generator output and station DC system
Output Power Supply	Matched with generator set control system	Used for excitation control, speed regulation and other functions
Allowable Voltage Difference	Generally ≤ ±5%～±10% rated voltage	Closing will be blocked if exceeded
Allowable Frequency Difference	Generally ≤ ±0.1～0.5Hz	Closing will be blocked if exceeded
Allowable Phase Difference (Closing Angle Difference)	Generally ≤ ±5°～±10°	Closing will be blocked if exceeded
Speed Regulation Range	Subject to unit requirements, usually over ±10% of rated speed	Wider range brings better adaptability
Frequency & Voltage Regulation Accuracy	Voltage: Class ≤0.5; Frequency: Class ≤0.1	Higher accuracy reduces grid-connection impact
Response Time	Preferably shorter, generally ≤ 100ms	Faster response ensures timely handling of emergencies
Operating Temperature	-5℃～+40℃ or wider range	Adapt to actual operating environment
Protection Class	IP54 and above	Good dustproof and waterproof performance
Communication Interface	RS-485 / MODBUS RTU / Ethernet (model dependent)	Baud rate such as 9600 is adjustable
Cabinet Dimension	Common size: 2260mm × 800mm × 600mm	Customizable as required

Recommendations for Selecting Units of Different Sizes

Unit Scale	Selection Recommendation
Large-scale Units (Thermal/Hydropower ≥60MW)	Adopt high-precision and high-reliability synchronization panels with complete automatic precise synchronization function, multi-circuit switching capacity and communication interfaces. Products equipped with high-speed DSP processing chips are preferred.
Medium-scale Units (10MW～60MW)	Select cost-effective synchronization panels with full functions, which must support both automatic and manual operation modes.
Small Units / Waste Heat Power Generation / Isolated Power Stations	Choose devices with basic synchronization functions, focusing on cost performance and easy maintenance.

Summary

• The generator synchronization panel ensures phase sequence consistency, accurately monitors and adjusts voltage, frequency and phase difference in automatic or manual mode, and sends closing commands only when all parameters are within safe allowable limits.

FAQ

Q：How to Buy Generator Synchronization Panel？

A:Generator Synchronization Panel Factory, a Chinese manufacturer specializing in the production of power products such as relay protection and generator synchronization panels. Please feel free to contact us via WhatsApp at 1365813266.

Q What is a Generator Synchronization Panel?

A dedicated control panel to safely connect on-grid generators with the main grid or another generator, matching voltage, frequency and phase angle before closing the circuit breaker.

Q Core purpose

Avoid out-of-phase closing which causes huge impact current, generator damage and grid disturbance.

Q Key built-in functions

Voltage/frequency measurement, phase difference monitoring, manual/automatic synchronization, synch check interlock, closing pulse output, alarm & fault indication.

Q Two synchronization modes

1. Manual Sync: Operator adjusts governor and excitation to align parameters then close breaker.
2. Auto Sync: The panel automatically tunes speed & voltage and sends closing command at the ideal moment.

Q What 4 conditions must be satisfied to parallel?

1. Equal voltage magnitude
2. Identical frequency
3. Same phase sequence
4. Phase angle difference within allowed range (typically ≤10°)

Q What happens if synchronizing out of phase?

Severe torque shock to generator shaft, winding overcurrent, trip of protection devices, even mechanical deformation and grid fluctuation.

Q Anti-parallel & interlock design

Equipped with synch check relay; breaker closing circuit is locked when phase difference exceeds threshold to prevent misclosing.

Q Linkage with generator protection

If generator differential (87G), reverse power (32) or overcurrent protection trips, synchronization function is blocked immediately.

Q Allowable synchronization window

Phase angle: 5°~15°; frequency difference: 0.1~0.2Hz; voltage deviation within ±5% rated value.

Q Closing advance angle

The panel outputs closing signal in advance to compensate breaker mechanical closing delay (usually 50~200ms).

Q Cannot complete synchronization

PT wiring error, wrong phase sequence, governor unable to stabilize frequency, excitation system fails to regulate voltage.

Q Automatic sync sends no closing order

Phase difference never enters the permissible window, synch interlock activated, panel control power lost or breaker position signal abnormal.

Q Site commissioning items

PT polarity & phase sequence verification, synch relay threshold calibration, simulated paralleling test, interlock blocking test.

Q Daily maintenance

Check indicator lights and voltage/frequency display regularly; lock synchronization function during generator overhaul.

Q Synch Panel vs Synch Check Relay

The synchronization panel integrates measuring, control and output circuits; a synch check relay is only a single interlock component installed inside switchgear.