443H Motor Self-Balancing Differential Protection

Description

Overview of Motor Self-Balancing Differential Protection

• Self-balancing differential protection for motors is a relatively uncommon type of motor protection implemented by relay for motor protection.
• For motors adopting self balancing differential protection motor schemes, medium voltage motor differential protection and the self-balancing differential protection function must be properly configured; this device is applicable to the protection and monitoring of both high‑voltage and low‑voltage asynchronous motors.

Transverse Differential Protection Logic Diagram

Protection Configuration（ANSI）

• Magnetic Balanced Differential Protection  87M
• Overcurrent Stage I  50/51
• Overcurrent Stage II  50/51
• Overcurrent Stage III  50/51
• Inverse-time Overcurrent  51
• Overload Protection  49
• Stall Protection  51LR
• Negative-sequence Overcurrent Stage I  46
• Negative-sequence Overcurrent Stage II  46
• Negative-sequence Inverse-time Overcurrent  46
• Zero-sequence Overcurrent  50N/51N
• Thermal Overload Protection  49
• Long Start-up Time Protection  48
• Motor Start Blocking
• Overvoltage Protection  59
• Undervoltage Protection  27
• Zero-sequence Overvoltage  59N
• Overfrequency Protection  81O
• Underfrequency Protection  81U
• PT Circuit Break  60
• PT Voltage Loss  60
• Control Circuit Break
• System Power Loss
• Non-electrical Protection  63

Measurement and Control Functions

Item	Parameters & Description
Bus voltage	Ua, Ub, Uc, Uab, Ubc, Uca
Measured current	Ia, Ic
Power	Active power P, Reactive power Q, Power factor COSφ
Frequency	f
Electric energy	EP+, EP-, EQ+, EQ-
Binary input	21 active channels (AC/DC 220V, DC 100V, DC 48V; specify upon order)
Output channels	11 protection outputs, 2 signal outputs, 1 closing position signal output, 1 device power loss output

Other Features

Item	Description
Communication Interfaces	1 Ethernet port 2 RS-485 ports (the second RS-485 port is multiplexed with time synchronization port, select function via configuration)
Communication Protocols	Ethernet: IEC 60870-103, IEC 61850 RS-485: MODBUS RTU
Time Synchronization	Communication message synchronization, SNTP, IRIG-B

Setting Table

No.	Setting Name	Setting Range	Unit	Default Value	Remarks
1	Motor Rated Current	0.1–100	A	5
2	Magnetic Balance Differential Setting	0.1–100	A	5
3	Motor Start-up Time	0–600	S	5
4	Overcurrent Stage I Setting	0.1–100	A	8
5	Overcurrent Stage II Setting	0.1–100	A	7
6	Overcurrent Stage II Time Delay	0–100	S	0.5
7	Overcurrent Stage III Setting	0.1–100	A	5
8	Overcurrent Stage III Time Delay	0–100	S	1
9	Inverse-time Overcurrent Setting	0.1–100	A	5
10	Inverse-time Overcurrent Time Delay	0–100	S	1
11	Inverse-time Overcurrent Type	0–3	—	1	1=Normal, 2=Severe, 3=Extreme
12	Overload Setting	0.1–100	A	5
13	Overload Time Delay	0–100	S	2
14	Overload Type	0–2	—	1	0=Disabled, 1=Trip, 2=Alarm
15	Stall Protection Setting	0.1–100	A	2
16	Stall Protection Time Delay	0–100	S	1
17	Negative-sequence Overcurrent Stage I Setting	0.1–100	A	2
18	Negative-sequence Overcurrent Stage I Time Delay	0–100	S	1
19	Negative-sequence Overcurrent Stage II Setting	0.1–100	A	1
20	Negative-sequence Overcurrent Stage II Time Delay	0–100	S	2
21	Negative-sequence Overcurrent Stage II Type	0–2	—	1	0=Disabled, 1=Trip, 2=Alarm
22	Negative-sequence Overcurrent Stage II Setting	0.1–100	A	1
23	Negative-sequence Overcurrent Stage II Time Delay	0–100	S	2
24	Negative-sequence Overcurrent Stage II Type	0–2	—	1	0=Disabled, 1=Trip, 2=Alarm
25	Zero-sequence Overcurrent Setting	0.1–100	A	2
26	Zero-sequence Overcurrent Time Delay	0–100	S	2
27	Zero-sequence Overcurrent Type	0–2	—	1	0=Disabled, 1=Trip, 2=Alarm
28	Negative-sequence Thermal Coefficient	2–10	—	6	Default: 6
29	Thermal Time Constant	0.01–100	min	5
30	Heat Dissipation Time Constant	1–5	Times	5	Normally 1~5 times of thermal time constant
31	Thermal Overload Alarm Level	10%–100%	%	80
32	Long Start-up Time Setting	0.1–100	A	5
33	Long Start-up Time Enable Duration	0–100	S	3
34	Start Interval Time Setting	0–100	min	10
35	Low Voltage Block Start Setting	1–400	V	70
36	Overvoltage Setting	1–600	V	120
37	Overvoltage Time Delay	0–100	S	0.5
38	Undervoltage Setting	1–400	V	80
39	Undervoltage Time Delay	0–100	S	1
40	Zero-sequence Overvoltage Setting	1–400	V	30
41	Zero-sequence Overvoltage Time Delay	0–100	S	0.5
42	Zero-sequence Overvoltage Type	0–2	—	1	0=Disabled, 1=Trip, 2=Alarm
43	Underfrequency Protection Setting	35–60	Hz	49
44	Underfrequency Protection Time Delay	0–100	S	0.5
45	Overfrequency Protection Setting	35.0–65	Hz	51
46	Overfrequency Protection Time Delay	0–100	S	0.5
47	Low Voltage Block Frequency Setting	1–400	V	20
48	Slip Block Frequency Setting	1–30	Hz/S	3
49	PT Circuit Break Time Delay	0–100	S	5
50	PT Voltage Loss Time Delay	0–100	S	5
51	Control Circuit Break Time Delay	0–100	S	10
52	System Power Loss Type	0–2	—	1	0=Disabled, 1=Trip, 2=Alarm
53	High Temperature Alarm Time Delay	0–100	S	0.1
54	High Temperature Trip Time Delay	0–100	S	0.1
55	Non-electrical Protection 1 Type	0–2	—	1	0=Disabled, 1=Trip, 2=Alarm
56	Non-electrical Protection 1 Time Delay	0–100	S	0.1
57	Non-electrical Protection 2 Type	0–2	—	1	0=Disabled, 1=Trip, 2=Alarm
58	Non-electrical Protection 2 Time Delay	0–100	S	0.1

motor differential protection diagram

Outline and Installation Dimensions

   

FAQ

Q：What tests must be performed on motor differential protection devices before they are officially put into service?

A:Before putting digital motor protection relays into service, multiple tests such as accuracy verification, functional inspection and motor differential protection stability test must be carried out; only after meeting specification requirements can the relay motor protection systems be officially commissioned.

Q: Advantage vs conventional longitudinal differential?

A: Only 3 single-window CTs needed instead of 6 separate CTs; less wiring, lower installation cost, higher ground-fault detecting sensitivity.