The ac-mains circuit supplying power to DMS-PS-CM supplies must be fused according to the current rating of the wire gauge used, in accordance with applicable regulatory codes. The built-in 1ampere line fuse (F1) only protects the module itself from destructive over currents.
5.AC Mains Connections (TB4): To ensure EMI-compliant operation, all three ac-supply inputs must be properly connected to TB4. Never operate any DMS- PS-CM power supply without a ground connection to TB4’s ‘FG’ terminal.
On 120Vac 50/60Hz mains, connect the black or "hot" lead to ‘AC(L)’, the white or “neutral” lead to ‘AC(N)’, and the supply ground (earth) to ‘FG’ (Frame Ground). On 220V 50/60Hz ac mains with line and neutral conductor-designa- tions, connect the line to AC(L), the neutral to AC(N), and the ground to ‘FG’.
6.Connector Torque Ratings: It is extremely important to tighten all input and output terminal blocks securely. TB4’s screw terminals must be torqued to
4.4 pound-inches (0.5Nm). TB1, TB2, and TB3 must be torqued to 3.6 pound- inches (0.4Nm). Proper tightening will minimize losses and ensure safe, reliable operation.
7.‘Power On’ LED: The Power On LED indicates that the unit has ac-power applied and its V1 dc-output is operational. However, the power-on LED’s illumination does not imply nor guarantee that the unit’s dc-outputs are within their specified accuracy.
8.Output Adjustment: The main output, V1, on all 5, 10, and 16W models is adjustable by approximately –10% to +15%. V1’s adjustment potentiometer is accessed via a small hole located next to the Power-On LED. While not recommended, field adjustment of single-output models can be performed within the tolerance window noted above. However, keep in mind that the unit’s maximum output power capability must not be exceeded. For example, increasing V1’s output voltage by 10% produces a corresponding 10% reduc- tion in V1’s maximum output current.
On dual-and triple-output units, V1 is factory calibrated with all outputs simultaneously loaded to 100% of their rated current. On all dual- and triple output models, adjusting V1 under any condition other than those just noted (i.e., all outputs loaded to their full rated current) will
DMS-PS-CM Series
High Efficiency, AC/DC Instrumentation Power Supplies with Individually Isolated Outputs
adversely affect the operation and stability of auxiliary outputs V2 and V3. On these models, V1 must be adjusted to within ±2 % of its nominal value (+5.0V, +12.0V, or +24.0V, depending on model).
9.Temperature Derating (See Figure 3): All DMS-PS-CM supplies are speci- fied to operate at their full rated power over the temp range of 0°C to +50°C in still air (convection cooling) without any thermal derating. For operation over +50°C in still air, derate the output power linearly by 2.5% per °C down to 50% rated power at +70°C. To operate the units at full rated power between +50°C and +70°C, a minimum forced-airflow of 100 LFM is required. For operation below 0°C, derate the output power linearly by 2.0% per °C down to 50% rated power at –25°C.
Unless forced air with the velocity noted above is employed, DMS-PS-CM supplies should never be mounted upside down (terminal blocks facing down). Also, always provide sufficient clearances in order to ensure adequate airflow around the supply.
10.V1 Peak Capabilities: DMS-PS-CM power supplies have a maximum continuous output-current rating that’s specified in the Ordering and Selection Guide. In addition, each model’s V1 output can intermittently supply 120% of its continuous rated current for short periods of time if the duty cycle is less than 10%. Peak current ratings do not apply to the auxiliary outputs V2 or V3.
11.Isolated Outputs: Unlike the majority of competitive ac/dc power supplies, all dual- and triple-output DMS-PS-CM power supplies feature fully-isolated outputs. This is an important feature when, for reasons of high common mode voltages, an instrument’s input circuit must be isolated from the system ground. All V1 outputs are isolated from the ac mains by a minimum of 3000Vac, while auxiliary outputs V2 and V3 are isolated from one another by 2000Vdc, and fromV1 by 1000Vdc. The low noise, double-isolated auxiliaries are ideal for powering sensitive instrumentation that requires low ac leakage-currents.
All ac/dc and dc/dc power components utilized in the construction of DMS- PS-CM power supplies are 100% hi-pot tested during their manufacturing pro- cesses. In addition, after final assembly by MPS, all models are subjected to an additional hi-pot testing consisting of 1000Vac sequentially applied between the ac mains input and each output, and between each output and all other outputs.
