Model 648 Specifications


TypeBipolar, 4-quadrant, DC current source
Current generationFully linear regulation with digital setting and analog control
Current range ±135 A
Compliance voltage (DC) ±75 V
Power 9.1 kW nominal
Nominal load 0.5 Ω, 0.5 H
Maximum load resistance0.55 Ω for ±135 A DC operation at +10% to -5% line voltage
Minimum load resistance0.41 Ω for ±135 A DC operation at +5% to -10% line voltage
Load inductance range0 H to 1 H
Current ripple10 mA RMS (0.007%) at 135 A into nominal load
Current ripple frequency Dominated by the line frequency and its harmonics
Temperature coefficient ±50 ppm of full scale/°C
Line regulation±75 ppm of full scale/10% line change
Stability (1 h)2 mA/h (after warm-up, internal setting)
Stability (24 h) 10 mA/24 h (typical, internal setting, dominated by temperature coefficient and line regulation)
Isolation Differential output is optically isolated from chassis to prevent ground loops
Slew rate 50 A/s into nominal load (dominated by magnet characteristics), 100 A/s maximum into a resistive load
Setting time<1 s for 10% step to within 1 mA of output into nominal load
Harmonic distortion≤0.1 Hz at ±135 A sine wave into resistive load, <0.02% THD; ≤10 Hz at ±10 A sine wave into resistive load, <0.30% THD
Attenuation-0.5 dB at 10 Hz
ProtectionShort circuit, line loss, low line voltage, high line voltage, output over voltage, output over current, and over temperature
ConnectorTwo lugs with 8.64 mm (0.34 in) holes for M8 or 5/16 in bolts

Output programming

Internal current setting
Resolution 1.0 mA (20 bit)
Settling time 600 ms for 1% step to within 1 mA (of internal setting)
Accuracy ±20 mA ±0.05% of setting
Operation Keypad, computer interface
ProtectionProgrammable current setting limit
Internal current ramp 
Ramp rate 0.1 mA/s to 50.000 A/s (compliance limited)
Update rate 12.3 increments/s
Ramp segments 5
Operation Keypad, computer interface
Protection Programmable ramp rate limit
External current programming
Sensitivity10 V/135 A
Resolution Analog
Accuracy ±20 mA ±1% of setting
Input resistance 20 kΩ differential; 50 kΩ common-mode
Operation Voltage program through rear panel, can be summed with internal current setting
LimitsInternally clamped at ±10.1 V and bandwidth limited -3 dB at 40 Hz (two pole, low pass filter)
ConnectorShared 15-pin D-sub


Output current
Resolution 1.0 mA
Accuracy±20 mA ±0.05% of rdg
Update rate2.5 rdg/s display, 10 rdg/s interface
Output voltage (at supply terminals)
Resolution1.0 mV
Accuracy±10 mV ±0.05% of rdg
Update rate 2.5 rdg/s display, 5 rdg/s interface

Front panel

Display type8-line by 40-character, graphic vacuum fluorescent display module
Display readingsOutput current, output voltage, and internal water temperature
Display settings Output current and ramp rate
Display annunciators Status and errors
LED annunciatorsFault, Compliance, Power Limit, Ramping, Remote
Audible annunciatorErrors and faults
Keypad type 20 full-travel keys
Keypad functions Direct access to common operations, menu-driven setup
PowerGreen flush ON and red extended OFF push buttons


IEEE-488.2 interface
FeaturesSH1, AH1, T5, L4, SR1, RL1, PP0, DC1, DT0, C0, E1
Reading rate To 10 rdg/s
Software support

LabVIEW™ driver
USB interface
FunctionEmulates a standard RS-232 serial port
Baud rates 57,600
Reading rate To 10 rdg/s
ConnectorType B USB connector
Software support

LabVIEW™ driver
Output current monitor
Sensitivity7 V/135 A
Accuracy±1% of full scale
Noise5 mV RMS
Source impedance 20 Ω
Shared 15-pin D-sub
Output voltage monitor
Sensitivity7 V/70 V
Accuracy1% of full scale
Noise2 mV RMS
Source impedance20 Ω
Shared 15-pin D-sub
Power supply cooling water
Remote enable inputTTL low or contact closure to enable output; used for mandatory 1 gal/min flow switch (included)
2-pin detachable terminal block connector
Valve power output24 VAC at 1.5 A maximum, automatic or manual control
2-pin detachable terminal block connector
Water valve optional
Magnet cooling water
Remote enable inputTTL low or contact closure to enable output; jumper required if unused
Valve power output24 VAC at 1.5 A maximum, automatic or manual control
Shared 4-pin detachable terminal block connector 
Flow, temperature switch and water valve not included
Emergency stop Requires 1 A, 24 VAC normally closed (NC) contact  to enable power-up; jumper required if unused
Fault output Relay with normally open (NO) or normally closed (NC) contact, 30 VDC at 1 A
Remote enable input TTL low or contact closure to enable output; jumper required if unused
Shared 8-pin detachable terminal block connector 
Emergency stop and inhibit switches not included


Line power
Power15.5 kVA max
Voltage and current 200 VAC ±5%, 41 A/phase
208 VAC ±5%, 40 A/phase
220 VAC ±5%, 38 A/phase
230 VAC ±5%, 37 A/phase
380 VAC ±5%, 23 A/phase
400 VAC ±5%, 21 A/phase
415 VAC ±5%, 21 A/phase
Protection3-phase thermal relay with adjustable current setting; two class CC 2 A fuses; over-voltage lockout circuit
Frequency 50 Hz or 60 Hz
Configuration 3-phase delta
Connector4-pin terminal block
Line voltage must be specified at time of order but is field reconfigurable; cable from power supply to facility power not included
Cooling water
Flow rate 7.6 L (2.0 gal)/min minimum
Maximum pressure 552 kPa (80 psi)
Pressure drop 159 kPa (23 psi) at 7.6 L (2.0 gal)/min minimum for power supply and mandatory flow switch
Temperature15 °C to 30 °C (non-condensing)
Two 12.7 mm (0.5 in) hose barbs
CAUTION: Internal condensation can cause damage to the power supply
Enclosure type

Custom 19 in rack cabinet

559 mm W × 1054 mm H × 673 mm D (22 in × 42 in × 26 in)
225 kg (495 lb)
Shipping size

914 mm W × 1219 mm H × 1168 mm D
(36 in × 48 in × 46 in)
Shipping weight
281 kg (620 lb)
Ambient temperature

15 °C to 35 °C at rated accuracy, 5 °C to 40 °C at reduced accuracy
30 min at output current setting
Approvals CE mark—low voltage compliance to EN61010-1, EMC compliance to EN61326-1